c++ notes
Must Watch!
Syntax
Create a simple "Hello World" program
#include <iostream>
using namespace std;
“using namespace std;” considered bad practice
You are using two libraries called Foo and Bar:
using namespace foo;
using namespace bar;
Everything works fine, and you can call Blah() from Foo and Quux() from Bar without problems.
But one day you upgrade to a new version of Foo 2.0, which now offers a function called Quux().
Now you've got a conflict: Both Foo 2.0 and Bar import Quux() into your global namespace.
This is going to take some effort to fix, especially if the function parameters happen to match.
If you had used foo::Blah() and bar::Quux(), then the introduction of foo::Quux() would have been a non-event.
The statement using namespace std is generally considered bad practice.
The alternative to this statement is to specify the namespace to which the identifier belongs using the scope operator(::) each time we declare a type.
Although the statement saves us from typing std:: whenever we wish to access a class or type defined in the std namespace, it imports the entirety of the std namespace into the current namespace of the program.
Let us take a few examples to understand why this might not be such a good thing
#include <foo>
#include <iostream>
// Use cout of std library
std::cout << "Something to display";
// Use cout of foo library
foo::cout < "Something to display";
int main() {
cout << "Hello World!";
return 0;
}
Output/Print
Use cout to output values/print text
#include <iostream>
using namespace std;
int main() {
cout << "Hello World!";
return 0;
}
Using many cout objects
#include <iostream>
using namespace std;
int main() {
cout << "Hello World!";
cout << "I am learning C++";
return 0;
}
Insert a new line with \n
#include <iostream>
using namespace std;
int main() {
cout << "Hello World! \n";
cout << "I am learning C++";
return 0;
}
Insert a new line with endl
#include <iostream>
using namespace std;
int main() {
cout << "Hello World!" << endl;
cout << "I am learning C++";
return 0;
}
Comments
Single-line comment before a line of code
#include <iostream>
using namespace std;
int main() {
// This is a comment
cout << "Hello World!";
return 0;
}
Single-line comment at the end of a line of code
#include <iostream>
using namespace std;
int main() {
cout << "Hello World!"; // This is a comment
return 0;
}
Multi-line comment
#include <iostream>
using namespace std;
int main() {
/* The code below will print the words Hello World!
to the screen, and it is amazing */
cout << "Hello World!";
return 0;
}
Variables
Create an integer variable
#include <iostream>
using namespace std;
int main() {
int myNum = 15;
cout << myNum;
return 0;
}
Create a variable without assigning the value, and assign the value later
#include <iostream>
using namespace std;
int main() {
int myNum;
myNum = 15;
cout << myNum;
return 0;
}
Assign a new value to an existing value (this will overwrite the previous value)
#include <iostream>
using namespace std;
int main() {
int myNum = 15; // Now myNum is 15
myNum = 10; // Now myNum is 10
cout << myNum;
return 0;
}
Create an unchangeable variable with the const keyword
#include <iostream>
using namespace std;
int main() {
const int myNum = 15;
myNum = 10;
cout << myNum;
return 0;
}
Combine text and a variable on print
#include <iostream>
using namespace std;
int main() {
int myAge = 35;
cout << "I am " << myAge << " years old.";
return 0;
}
Add a variable to another variable
#include <iostream>
using namespace std;
int main() {
int x = 5;
int y = 6;
int sum = x + y;
cout << sum;
return 0;
}
Declare many variables of the same type with a comma-separated list
#include <iostream>
using namespace std;
int main() {
int x = 5, y = 6, z = 50;
cout << x + y + z;
return 0;
}
Identifiers
#include <iostream>
using namespace std;
int main() {
// Good name
int minutesPerHour = 60;
// OK, but not so easy to understand what m actually is
int m = 60;
cout << minutesPerHour << "\n";
cout << m;
return 0;
}
User Input
Input a number and print the result
#include <iostream>
using namespace std;
int main() {
int x;
cout << "Type a number: "; // Type a number and press enter
cin >> x; // Get user input from the keyboard
cout << "Your number is: " << x;
return 0;
}
Input two numbers and print the sum
#include <iostream>
using namespace std;
int main() {
int x, y;
int sum;
cout << "Type a number: ";
cin >> x;
cout << "Type another number: ";
cin >> y;
sum = x + y;
cout << "Sum is: " << sum;
return 0;
}
Data Types
A demonstration of different data types
#include <iostream>
#include <string>
using namespace std;
int main () {
// Creating variables
int myNum = 5; // Integer (whole number)
float myFloatNum = 5.99; // Floating point number
double myDoubleNum = 9.98; // Floating point number
char myLetter = 'D'; // Character
bool myBoolean = true; // Boolean
string myString = "Hello"; // String
// Print variable values
cout << "int: " << myNum << "\n";
cout << "float: " << myFloatNum << "\n";
cout << "double: " << myDoubleNum << "\n";
cout << "char: " << myLetter << "\n";
cout << "bool: " << myBoolean << "\n";
cout << "string: " << myString << "\n";
return 0;
}
Create an int type
#include <iostream>
using namespace std;
int main () {
int myNum = 1000;
cout << myNum;
return 0;
}
Create a float type
#include <iostream>
using namespace std;
int main () {
float myNum = 5.75;
cout << myNum;
return 0;
}
Create a double type
#include <iostream>
using namespace std;
int main () {
double myNum = 19.99;
cout << myNum;
return 0;
}
Create boolean types
#include <iostream>
using namespace std;
int main() {
bool isCodingFun = true;
bool isFishTasty = false;
cout << isCodingFun << "\n";
cout << isFishTasty;
return 0;
}
Create a char type
#include <iostream>
using namespace std;
int main () {
char myGrade = 'B';
cout << myGrade;
return 0;
}
Create a string type
#include <iostream>
#include <string>
using namespace std;
int main() {
string greeting = "Hello";
cout << greeting;
return 0;
}
Operators
Addition operator
#include <iostream>
using namespace std;
int main() {
int x = 100 + 50;
cout << x;
return 0;
}
Increment operator
#include <iostream>
using namespace std;
int main() {
int x = 10;
++x;
cout << x;
return 0;
}
Assignment operator
#include <iostream>
using namespace std;
int main() {
int x = 10;
cout << x;
return 0;
}
Addition assignment operator
#include <iostream>
using namespace std;
int main() {
int x = 10;
x += 5;
cout << x;
return 0;
}
Strings
Create a string
#include <iostream>
#include <string>
using namespace std;
int main() {
string greeting = "Hello";
cout << greeting;
return 0;
}
String concatenation
#include <iostream>
#include <string>
using namespace std;
int main () {
string firstName = "John ";
string lastName = "Doe";
string fullName = firstName + lastName;
cout << fullName;
return 0;
}
String length
#include <iostream>
#include <string>
using namespace std;
int main() {
string txt = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
cout << "The length of the txt string is: " << txt.length();
return 0;
}
Access string characters
#include <iostream>
#include <string>
using namespace std;
int main() {
string myString = "Hello";
cout << myString[0];
return 0;
}
Change string characters
#include <iostream>
#include <string>
using namespace std;
int main() {
string myString = "Hello";
myString[0] = 'J';
cout << myString;
return 0;
}
User input strings
#include <iostream>
#include <string>
using namespace std;
int main() {
string fullName;
cout << "Type your full name: ";
getline (cin, fullName);
cout << "Your name is: " << fullName;
return 0;
}
Math
Find the highest value of two numbers
#include <iostream>
using namespace std;
int main() {
cout << max(5, 10);
return 0;
}
Find the lowest value of two numbers
#include <iostream>
using namespace std;
int main() {
cout << min(5, 10);
return 0;
}
Use the cmath header file for other math functions
#include <iostream>
#include <cmath>
using namespace std;
int main() {
cout << sqrt(64) << "\n";
cout << round(2.6) << "\n";
cout << log(2) << "\n";
return 0;
}
Booleans
Boolean values
#include <iostream>
using namespace std;
int main() {
bool isCodingFun = true;
bool isFishTasty = false;
cout << isCodingFun << "\n";
cout << isFishTasty;
return 0;
}
Compare two values
#include <iostream>
using namespace std;
int main() {
cout << (10 > 9);
return 0;
}
Compare two variables
#include <iostream>
using namespace std;
int main() {
int x = 10;
int y = 9;
cout << (x > y);
return 0;
}
If...Else (Conditions)
The if statement
#include <iostream>
using namespace std;
int main() {
if (20 > 18) {
cout << "20 is greater than 18";
}
return 0;
}
The else statement
#include <iostream>
using namespace std;
int main() {
int time = 20;
if (time < 18) {
cout << "Good day.";
} else {
cout << "Good evening.";
}
return 0;
}
The else if statement
#include <iostream>
using namespace std;
int main() {
int time = 22;
if (time < 10) {
cout << "Good morning.";
} else if (time < 20) {
cout << "Good day.";
} else {
cout << "Good evening.";
}
return 0;
}
Switch
The switch statement
#include <iostream>
using namespace std;
int main() {
int day = 4;
switch (day) {
case 1:
cout << "Monday";
break;
case 2:
cout << "Tuesday";
break;
case 3:
cout << "Wednesday";
break;
case 4:
cout << "Thursday";
break;
case 5:
cout << "Friday";
break;
case 6:
cout << "Saturday";
break;
case 7:
cout << "Sunday";
break;
}
return 0;
}
The switch statement with a default keyword
#include <iostream>
using namespace std;
int main() {
int day = 4;
switch (day) {
case 6:
cout << "Today is Saturday";
break;
case 7:
cout << "Today is Sunday";
break;
default:
cout << "Looking forward to the Weekend";
}
return 0;
}
Loops
While loop
#include <iostream>
using namespace std;
int main() {
int i = 0;
while (i < 5) {
cout << i << "\n";
i++;
}
return 0;
}
Do while loop
#include <iostream>
using namespace std;
int main() {
int i = 0;
do {
cout << i << "\n";
i++;
}
while (i < 5);
return 0;
}
For loop
#include <iostream>
using namespace std;
int main() {
for (int i = 0; i < 5; i++) {
cout << i << "\n";
}
return 0;
}
Break a loop
#include <iostream>
using namespace std;
int main() {
for (int i = 0; i < 10; i++) {
if (i == 4) {
break;
}
cout << i << "\n";
}
return 0;
}
Continue a loop
#include <iostream>
using namespace std;
int main() {
for (int i = 0; i < 10; i++) {
if (i == 4) {
continue;
}
cout << i << "\n";
}
return 0;
}
Arrays
Create and access an array
#include <iostream>
#include <string>
using namespace std;
int main() {
string cars[4] = {"Volvo", "BMW", "Ford", "Mazda"};
cout << cars[0];
return 0;
}
Change an array element
#include <iostream>
#include <string>
using namespace std;
int main() {
string cars[4] = {"Volvo", "BMW", "Ford", "Mazda"};
cars[0] = "Opel";
cout << cars[0];
return 0;
}
Loop through an array
#include <iostream>
#include <string>
using namespace std;
int main() {
string cars[4] = {"Volvo", "BMW", "Ford", "Mazda"};
for(int i = 0; i < 4; i++) {
cout << cars[i] << "\n";
}
return 0;
}
References
Create a reference variable
#include <iostream>
#include <string>
using namespace std;
int main() {
string food = "Pizza";
string &meal = food;
cout << food << "\n";
cout << meal << "\n";
return 0;
}
Access the memory address of a variable
#include <iostream>
#include <string>
using namespace std;
int main() {
string food = "Pizza";
cout << &food;
return 0;
}
Pointers
Create a pointer variable
#include <iostream>
#include <string>
using namespace std;
int main() {
string food = "Pizza"; // A string variable
string* ptr = &food; // A pointer variable that stores the address of food
// Output the value of food
cout << food << "\n";
// Output the memory address of food
cout << &food << "\n";
// Output the memory address of food with the pointer
cout << ptr << "\n";
return 0;
}
Get the value of a variable with the dereference operator *
#include <iostream>
#include <string>
using namespace std;
int main() {
string food = "Pizza"; // Variable declaration
string* ptr = &food; // Pointer declaration
// Reference: Output the memory address of food with the pointer
cout << ptr << "\n";
// Dereference: Output the value of food with the pointer
cout << *ptr << "\n";
return 0;
}
Modify the pointer value
#include <iostream>
#include <string>
using namespace std;
int main() {
string food = "Pizza";
string* ptr = &food;
// Output the value of food
cout << food << "\n";
// Output the memory address of food
cout << &food << "\n";
// Access the memory address of food and output its value
cout << *ptr << "\n";
// Change the value of the pointer
*ptr = "Hamburger";
// Output the new value of the pointer
cout << *ptr << "\n";
// Output the new value of the food variable
cout << food << "\n";
return 0;
}
Files
Create, write and read a text file
#include <iostream>
#include <fstream>
#include <string>
using namespace std;
int main () {
// Create a text file
ofstream MyWriteFile("filename.txt");
// Write to the file
MyWriteFile << "Files can be tricky, but it is fun enough!";
// Close the file
MyWriteFile.close();
// Create a text string, which is used to output the text file
string myText;
// Read from the text file
ifstream MyReadFile("filename.txt");
// Use a while loop together with the getline() function to read the file line by line
while (getline (MyReadFile, myText)) {
// Output the text from the file
cout << myText;
}
// Close the file
MyReadFile.close();
}
Functions
Create and call a function
#include <iostream>
using namespace std;
void myFunction() {
cout << "I just got executed!";
}
int main() {
myFunction();
return 0;
}
Call a function multiple times
#include <iostream>
using namespace std;
void myFunction() {
cout << "I just got executed!\n";
}
int main() {
myFunction();
myFunction();
myFunction();
return 0;
}
Function declaration and definition
#include <iostream>
using namespace std;
// Function declaration
void myFunction();
// The main method
int main() {
myFunction(); // call the function
return 0;
}
// Function definition
void myFunction() {
cout << "I just got executed!";
}
Parameters and arguments
#include <iostream>
#include <string>
using namespace std;
void myFunction(string fname) {
cout << fname << " Refsnes\n";
}
int main() {
myFunction("Liam");
myFunction("Jenny");
myFunction("Anja");
return 0;
}
Default parameter value
#include <iostream>
#include <string>
using namespace std;
void myFunction(string country = "Norway") {
cout << country << "\n";
}
int main() {
myFunction("Sweden");
myFunction("India");
myFunction();
myFunction("USA");
return 0;
}
Multiple parameters
#include <iostream>
#include <string>
using namespace std;
void myFunction(string fname, int age) {
cout << fname << " Refsnes. " << age << " years old. \n";
}
int main() {
myFunction("Liam", 3);
myFunction("Jenny", 14);
myFunction("Anja", 30);
return 0;
}
Return value
#include <iostream>
using namespace std;
int myFunction(int x) {
return 5 + x;
}
int main() {
cout << myFunction(3);
return 0;
}
Return the sum of two parameters
#include <iostream>
using namespace std;
int myFunction(int x, int y) {
return x + y;
}
int main() {
cout << myFunction(5, 3);
return 0;
}
Pass by reference
#include <iostream>
using namespace std;
void swapNums(int &x, int &y) {
int z = x;
x = y;
y = z;
}
int main() {
int firstNum = 10;
int secondNum = 20;
cout << "Before swap: " << "\n";
cout << firstNum << secondNum << "\n";
swapNums(firstNum, secondNum);
cout << "After swap: " << "\n";
cout << firstNum << secondNum << "\n";
return 0;
}
Function overloading
#include <iostream>
using namespace std;
int plusFuncInt(int x, int y) {
return x + y;
}
double plusFuncDouble(double x, double y) {
return x + y;
}
int main() {
int myNum1 = plusFuncInt(8, 5);
double myNum2 = plusFuncDouble(4.3, 6.26);
cout << "Int: " << myNum1 << "\n";
cout << "Double: " << myNum2;
return 0;
}
Classes/Objects
Create an object of a class and access class attributes
#include <iostream>
#include <string>
using namespace std;
class MyClass { // The class
public: // Access specifier
int myNum; // Attribute (int variable)
string myString; // Attribute (string variable)
};
int main() {
MyClass myObj; // Create an object of MyClass
// Access attributes and set values
myObj.myNum = 15;
myObj.myString = "Some text";
// Print values
cout << myObj.myNum << "\n";
cout << myObj.myString;
return 0;
}
Create multiple objects
#include <iostream>
#include <string>
using namespace std;
class Car {
public:
string brand;
string model;
int year;
};
int main() {
Car carObj1;
carObj1.brand = "BMW";
carObj1.model = "X5";
carObj1.year = 1999;
Car carObj2;
carObj2.brand = "Ford";
carObj2.model = "Mustang";
carObj2.year = 1969;
cout << carObj1.brand << " " << carObj1.model << " " << carObj1.year << "\n";
cout << carObj2.brand << " " << carObj2.model << " " << carObj2.year << "\n";
return 0;
}
Create class methods
#include <iostream>
using namespace std;
class MyClass { // The class
public: // Access specifier
void myMethod() { // Method/function
cout << "Hello World!";
}
};
int main() {
MyClass myObj; // Create an object of MyClass
myObj.myMethod(); // Call the method
return 0;
}
Define a class method outside the class definition
#include <iostream>
using namespace std;
class MyClass { // The class
public: // Access specifier
void myMethod(); // Method/function declaration
};
// Method/function definition outside the class
void MyClass::myMethod() {
cout << "Hello World!";
}
int main() {
MyClass myObj; // Create an object of MyClass
myObj.myMethod(); // Call the method
return 0;
}
Add parameters to a class method
#include <iostream>
using namespace std;
class Car {
public:
int speed(int maxSpeed);
};
int Car::speed(int maxSpeed) {
return maxSpeed;
}
int main() {
Car myObj;
cout << myObj.speed(200);
return 0;
}
Create a constructor
#include <iostream>
using namespace std;
class MyClass { // The class
public: // Access specifier
MyClass() { // Constructor
cout << "Hello World!";
}
};
int main() {
MyClass myObj; // Create an object of MyClass (this will call the constructor)
return 0;
}
Constructor parameters
#include <iostream>
using namespace std;
class Car { // The class
public: // Access specifier
string brand; // Attribute
string model; // Attribute
int year; // Attribute
Car(string x, string y, int z) { // Constructor with parameters
brand = x;
model = y;
year = z;
}
};
int main() {
// Create Car objects and call the constructor with different values
Car carObj1("BMW", "X5", 1999);
Car carObj2("Ford", "Mustang", 1969);
// Print values
cout << carObj1.brand << " " << carObj1.model << " " << carObj1.year << "\n";
cout << carObj2.brand << " " << carObj2.model << " " << carObj2.year << "\n";
return 0;
}
Constructor defined outside the class
#include <iostream>
using namespace std;
class Car { // The class
public: // Access specifier
string brand; // Attribute
string model; // Attribute
int year; // Attribute
Car(string x, string y, int z); // Constructor declaration
};
// Constructor definition outside the class
Car::Car(string x, string y, int z) {
brand = x;
model = y;
year = z;
}
int main() {
// Create Car objects and call the constructor with different values
Car carObj1("BMW", "X5", 1999);
Car carObj2("Ford", "Mustang", 1969);
// Print values
cout << carObj1.brand << " " << carObj1.model << " " << carObj1.year << "\n";
cout << carObj2.brand << " " << carObj2.model << " " << carObj2.year << "\n";
return 0;
}
Public and private specifiers
#include <iostream>
using namespace std;
class MyClass {
public: // Public access specifier
int x; // Public attribute
private: // Private access specifier
int y; // Private attribute
};
int main() {
MyClass myObj;
myObj.x = 25; // Allowed (x is public)
myObj.y = 50; // Not allowed (y is private)
return 0;
}
Encapsulation - hide sensitive data from users
#include <iostream>
using namespace std;
class Employee {
private:
int salary;
public:
void setSalary(int s) {
salary = s;
}
int getSalary() {
return salary;
}
};
int main() {
Employee myObj;
myObj.setSalary(50000);
cout << myObj.getSalary();
return 0;
}
Inheritance - inherit attributes and methods from one class to another
#include <iostream>
#include <string>
using namespace std;
// Base class
class Vehicle {
public:
string brand = "Ford";
void honk() {
cout << "Tuut, tuut! \n" ;
}
};
// Derived class
class Car: public Vehicle {
public:
string model = "Mustang";
};
int main() {
Car myCar;
myCar.honk();
cout << myCar.brand + " " + myCar.model;
return 0;
}
Multilevel inheritance
#include <iostream>
using namespace std;
// Parent class
class MyClass {
public:
void myFunction() {
cout << "Some content in parent class." ;
}
};
// Child class
class MyChild: public MyClass {
};
// Grandchild class
class MyGrandChild: public MyChild {
};
int main() {
MyGrandChild myObj;
myObj.myFunction();
return 0;
}
Multiple inheritance
#include <iostream>
using namespace std;
// Base class
class MyClass {
public:
void myFunction() {
cout << "Some content in parent class.\n" ;
}
};
// Another base class
class MyOtherClass {
public:
void myOtherFunction() {
cout << "Some content in another class.\n" ;
}
};
// Derived class
class MyChildClass: public MyClass, public MyOtherClass {
};
int main() {
MyChildClass myObj;
myObj.myFunction();
myObj.myOtherFunction();
return 0;
}
Polymorphism - perform a single action in different ways
#include <iostream>
#include <string>
using namespace std;
// Base class
class Animal {
public:
void animalSound() {
cout << "The animal makes a sound \n" ;
}
};
// Derived class
class Pig : public Animal {
public:
void animalSound() {
cout << "The pig says: wee wee \n" ;
}
};
// Derived class
class Dog : public Animal {
public:
void animalSound() {
cout << "The dog says: bow wow \n" ;
}
};
int main() {
Animal myAnimal;
Pig myPig;
Dog myDog;
myAnimal.animalSound();
myPig.animalSound();
myDog.animalSound();
return 0;
}
Files - Create, write and read a file
#include <iostream>
#include <fstream>
#include <string>
using namespace std;
int main () {
// Create a text file
ofstream MyWriteFile("filename.txt");
// Write to the file
MyWriteFile << "Files can be tricky, but it is fun enough!";
// Close the file
MyWriteFile.close();
// Create a text string, which is used to output the text file
string myText;
// Read from the text file
ifstream MyReadFile("filename.txt");
// Use a while loop together with the getline() function to read the file line by line
while (getline (MyReadFile, myText)) {
// Output the text from the file
cout << myText;
}
// Close the file
MyReadFile.close();
}
Exceptions - Handle errors
#include <iostream>
using namespace std;
int main() {
try {
int age = 15;
if (age > 18) {
cout << "Access granted - you are old enough.";
} else {
throw (age);
}
}
catch (int myNum) {
cout << "Access denied - You must be at least 18 years old.\n";
cout << "Age is: " << myNum;
}
return 0;
}
C++ Syntax
Let's break up the following code to understand it better:
Example
#include <iostream>
using namespace std;
int main() {
cout << "Hello World!";
return 0;
}
Run example »
Example explained
Line 1:
#include <iostream> is a header file library that lets us work with input and output objects, such as cout (used in line 5). Header files add functionality to C++ programs.
Line 2:
using namespace std means that we can use names for objects and variables from The standard library.
Don't worry if you don't understand how #include <iostream> and using namespace std works. Just think of it as something that (almost) always appears in your program.
Line 3: A blank line. C++ ignores white space.
Line 4: Another thing that always appear in a C++ program, is int main(). This is called a function. Any code inside its curly brackets {} will be executed.
Line 5:
cout (pronounced "see-out") is an object used together with the insertion operator (
<<) to output/print text. In our example it will output "Hello World".
Note: Every C++ statement ends with a semicolon ;.
Note: The body of int main() could also been written as:
int main () { cout << "Hello World! "; return 0;
}
Remember: The compiler ignores white spaces. However, multiple lines makes the code more readable.
Line 6:
return 0 ends the main function.
Line 7: Do not forget to add the closing curly bracket } to actually end The main function.
Omitting Namespace
You might see some C++ programs that runs without the standard namespace library. The using namespace std line can be omitted and replaced with The std keyword, followed by the :: operator
for some objects:
Example
#include <iostream>
int main() {
std::cout << "Hello World!";
return 0;
}
Run example »
It is up to you if you want to include the standard namespace library or not.
C++ Output (Print Text)
The cout object, together with The << operator, is used to output values/print text:
Example
#include <iostream>
using namespace std;
int main() {
cout << "Hello World!";
return 0;
}
Run example »
You can add as many cout objects as you want. However, note that it does not insert a new line at the end of the output:
Example
#include <iostream>
using namespace std;
int main() {
cout << "Hello World!";
cout << "I am learning C++";
return 0;
}
Run example »
C++ Output (Print Text)
The cout object, together with The <<
operator, is used to output values/print text:
Example
#include <iostream>
using namespace std;
int main() {
cout << "Hello World!";
return 0;
}
Run example »
You can add as many cout objects as you want. However, note that it does not insert a new line at the end of the output:
Example
#include <iostream>
using namespace std;
int main() {
cout << "Hello World!";
cout << "I am learning C++";
return 0;
}
Run example »
New Lines
to insert a new line, you can use The \n character:
Example
#include <iostream>
using namespace std;
int main() {
cout << "Hello World! \n";
cout << "I am learning C++";
return 0;
}
Run example »
Tip: Two
\n characters after each other will create a blank line:
Example
#include <iostream>
using namespace std;
int main() {
cout << "Hello World! \n\n";
cout << "I am learning C++";
return 0;
}
Run example »
Another way to insert a new line, is with The endl manipulator:
Example
#include <iostream>
using namespace std;
int main() {
cout << "Hello World!" << endl;
cout << "I am learning C++";
return 0;
}
Run example »
Both \n and endl are used to break lines.
However, \n is used more often and is the preferred way.
C++ Comments
Comments can be used to explain C++ code, and to make it more readable. It can also be used to prevent execution when testing alternative code. Comments can be singled-lined or multi-lined.
Single-line comments start with two forward slashes (//).
Any text between // and the end of the line is ignored by the compiler (will not be executed).
This example uses a single-line comment before a line of code:
Example
// This is a comment
cout << "Hello World!";
Run example »
This example uses a single-line comment at the end of a line of code:
Example
cout << "Hello World!"; // This is a comment
Run example »
C++ Multi-line Comments
Multi-line comments start with /* and ends with */.
Any text between /* and */ will be ignored by the compiler:
Example
/* The code below will print the words Hello World!to the screen, and it is amazing */
cout << "Hello World!";
Run example »
Single or multi-line comments?
It is up to you which you want to use. Normally, we use // for short comments, and /* */ for longer.
C++ Variables
Variables are containers for storing data values.
In C++, there are different types of variables (defined with different keywords), for example:
- int - stores integers (whole numbers), without decimals, such as 123 or -123
- double - stores floating point numbers, with decimals, such as 19.99 or -19.99
- char - stores single characters, such as 'a' or 'B'. Char values are surrounded by single quotes
- string - stores text, such as "Hello World". String values are surrounded by double quotes
- bool - stores values with two states: true or false
Declaring (Creating) Variables
to create a variable, you must specify the type and assign it a value:
Syntax
type variable = value;
Where type is one of C++ types (such as int), and variable is the name of the variable (such as x or myName). The equal sign is used to assign values to the variable. to create a variable that should store a number, look at the following example:
Example
Create a variable called myNum of type int and assign it the value 15:
int myNum = 15;
cout << myNum;
Run example »
You can also declare a variable without assigning the value, and assign the value later:
Example
int myNum;
myNum = 15;
cout << myNum;
Run example »
Note that if you assign a new value to an existing variable, it will overwrite the previous value:
Example
int myNum = 15; // myNum is 15
myNum = 10; // Now myNum is 10
cout << myNum; // Outputs 10
Run example »
Other Types
A demonstration of other data types:
Example
int myNum = 5;
// Integer (whole number without decimals)
double myFloatNum = 5.99;
// Floating point number (with decimals)
char myLetter = 'D';
// Character
string myText = "Hello";
// String (text)
bool
myBoolean = true; // Boolean (true or false)
You will learn more about the individual types in the Data Types chapter.
Display Variables
The cout object is used together with The << operator to display variables. to combine both text and a variable, separate them with The << operator:
Example
int myAge = 35;
cout << "I am " << myAge << " years old.";
Run example »
Add Variables Together
to add a variable to another variable, you can use The + operator:
Example
int x = 5;
int y = 6;
int sum = x + y;
cout << sum;
Run example »
C++ Variables
Variables are containers for storing data values.
In C++, there are different types of variables (defined with different keywords), for example:
- int - stores integers (whole numbers), without decimals, such as 123 or -123
- double - stores floating point numbers, with decimals, such as 19.99 or -19.99
- char - stores single characters, such as 'a' or 'B'. Char values are surrounded by single quotes
- string - stores text, such as "Hello World". String values are surrounded by double quotes
- bool - stores values with two states: true or false
Declaring (Creating) Variables
to create a variable, you must specify the type and assign it a value:
Syntax
type variable = value;
Where type is one of C++ types (such as int), and variable is the name of the variable (such as x or myName). The equal sign is used to assign values to the variable. to create a variable that should store a number, look at the following example:
Example
Create a variable called myNum of type int and assign it the value 15:
int myNum = 15;
cout << myNum;
Run example »
You can also declare a variable without assigning the value, and assign the value later:
Example
int myNum;
myNum = 15;
cout << myNum;
Run example »
Note that if you assign a new value to an existing variable, it will overwrite the previous value:
Example
int myNum = 15; // myNum is 15
myNum = 10; // Now myNum is 10
cout << myNum; // Outputs 10
Run example »
Other Types
A demonstration of other data types:
Example
int myNum = 5;
// Integer (whole number without decimals)
double myFloatNum = 5.99;
// Floating point number (with decimals)
char myLetter = 'D';
// Character
string myText = "Hello";
// String (text)
bool
myBoolean = true; // Boolean (true or
false)
You will learn more about the individual types in the Data Types chapter.
Display Variables
The cout object is used together with The << operator to display variables. to combine both text and a variable, separate them with The << operator:
Example
int myAge = 35;
cout << "I am " << myAge << " years old.";
Run example »
Add Variables Together
to add a variable to another variable, you can use The + operator:
Example
int x = 5;
int y = 6;
int sum = x + y;
cout << sum;
Run example »
Declare Many Variables
to declare more than one variable of the same type, use a comma-separated list:
Example
int x = 5, y = 6, z = 50;
cout <<
x + y + z;
Run example »
C++ Identifiers
All C++ variables must be
identified with unique names.
These unique names are called identifiers.
Identifiers can be short names (like x and y) or more descriptive names (age, sum, totalVolume).
Note: It is recommended to use descriptive names in order to create understandable and maintainable code:
Example
// Good
int minutesPerHour = 60;
// OK, but not so easy to understand what m actually is
int m = 60;
Run example »
The general rules for constructing names for variables (unique identifiers) are:
- Names can contain letters, digits and underscores
- Names must begin with a letter or an underscore (_)
- Names are case sensitive (myVar and myvar are different variables)
- Names cannot contain whitespaces or special characters like !, #, %, etc.
- Reserved words (like C++ keywords, such as int) cannot be used as names
Constants
When you do not want others (or yourself) to override existing variable values, use The const keyword (this will declare The variable as "constant", which means unchangeable and read-only):
Example
const int myNum = 15; // myNum will always be 15
myNum = 10; // error:
assignment of read-only variable 'myNum'
Run example »
You should always declare the variable as constant when you have values that are unlikely to change:
Example
const int minutesPerHour = 60;
const float PI = 3.14;
Run example »
C++ User Input
You have already learned that
cout is used to output (print) values. Now we will use
cin to get user input.
cin is a predefined variable that reads data from the keyboard with the extraction operator (
>>).
In the following example, the user can input a number, which is stored in The variable
x. Then we print the value of x:
Example
int x;
cout << "Type a number: "; // Type a number and press enter
cin >> x; // Get user
input from the keyboard
cout << "Your number is: " << x;
// Display the input value
Run example »
Good To Know
cout is pronounced "see-out". Used for output, and uses the insertion operator (
<<)
cin is pronounced "see-in". Used for input, and uses the extraction operator (
>>)
Creating a Simple Calculator
In this example, the user must input two numbers. Then we print The sum by calculating (adding) the two numbers:
Example
int x, y;
int sum;
cout << "Type a number: ";
cin >> x;
cout << "Type another number: ";
cin >>
y;
sum = x + y;
cout << "Sum is: " << sum;
Run example »
There you go! You just built a basic calculator!
C++ Data Types
As explained in the Variables chapter, a variable in C++ must be a specified data type:
Example
int myNum = 5;
// Integer (whole number)
float myFloatNum = 5.99;
// Floating point number
double myDoubleNum = 9.98; // Floating point number
char myLetter = 'D';
// Character
bool
myBoolean = true; // Boolean
string myText = "Hello";
// String
Run example »
Basic Data Types
The data type specifies the size and type of information the variable will store:
| Data Type |
Size |
Description |
|
int |
4 bytes |
Stores whole numbers, without decimals |
|
float |
4 bytes |
Stores fractional numbers, containing one or more decimals. Sufficient for
storing 7 decimal digits |
|
double |
8 bytes |
Stores fractional numbers, containing one or more decimals. Sufficient for
storing 15 decimal digits |
|
boolean |
1 byte |
Stores true or false values |
|
char |
1 byte |
Stores a single character/letter/number, or ASCII values |
You will learn more about the individual data types in the next chapters.
C++ Data Types
As explained in the Variables chapter, a variable in C++ must be a specified data type:
Example
int myNum = 5;
// Integer (whole number)
float myFloatNum = 5.99;
// Floating point number
double myDoubleNum = 9.98; // Floating point number
char myLetter = 'D';
// Character
bool
myBoolean = true; // Boolean
string myText = "Hello";
// String
Run example »
Basic Data Types
The data type specifies the size and type of information the variable will store:
| Data Type |
Size |
Description |
|
int |
4 bytes |
Stores whole numbers, without decimals |
|
float |
4 bytes |
Stores fractional numbers, containing one or more decimals. Sufficient for
storing 7 decimal digits |
|
double |
8 bytes |
Stores fractional numbers, containing one or more decimals. Sufficient for
storing 15 decimal digits |
|
boolean |
1 byte |
Stores true or false values |
|
char |
1 byte |
Stores a single character/letter/number, or ASCII values |
You will learn more about the individual data types in the next chapters.
Numeric Types
Use
int when you need to store a whole number without decimals, like 35 or 1000, and float or
double when you need a floating point number (with decimals), like 9.99 or 3.14515.
int
int myNum = 1000;
cout << myNum;
Run example »
float
float myNum = 5.75;
cout << myNum;
Run example »
double
double myNum = 19.99;
cout << myNum;
Run example »
float vs.
double
The precision of a floating point value indicates how many digits the value can have
after the decimal point.
The precision of float is only six or seven
decimal digits, while
double variables have a precision
of about 15 digits. Therefore it is safer to use
double for most calculations.
Scientific Numbers
A floating point number can also be a scientific number with an "e" to indicate the power of 10:
Example
float f1 = 35e3;
double d1 = 12E4;
cout << f1;
cout << d1;
Run example »
Boolean Types
A boolean data type is declared with The bool keyword and can only take the values
true or
false. When the value is returned, true
=
1 and false
=
0.
Example
bool isCodingFun = true;
bool isFishTasty = false;
cout << isCodingFun;
// Outputs 1 (true)
cout << isFishTasty; // Outputs 0 (false)
Run example »
Boolean values are mostly used for conditional testing, which you will learn more about in a later chapter.
Character Types
The char data type is used to store a single character. The character must be
surrounded by single quotes, like 'A' or 'c':
Example
char myGrade = 'B';
cout << myGrade;
Run example »
Alternatively, you can use ASCII values to display certain characters:
Example
char a = 65, b = 66, c = 67;
cout << a;
cout << b;
cout << c;
Run example »
Tip: A list of all ASCII values can be found in our ASCII Table Reference.
String Types
The string type is used to store a sequence of characters (text).
This is not a built-in type, but it behaves like one in its most basic usage.
You will learn more about strings, in our C++ Strings Chapter.
C++ Operators
Operators are used to perform operations on variables and values.
In the example below, we use the
+ operator to add together two values:
Example
int x = 100 + 50;
Run example »
Although The + operator is often used to add together two values, like in the example above, it can also be used to add together a variable and a value, or a variable and another variable:
Example
int sum1 = 100 + 50;
// 150 (100 + 50)
int sum2 = sum1 + 250; // 400 (150 + 250)
int sum3 = sum2 + sum2; // 800 (400 + 400)
Run example »
C++ divides the operators into the following groups:
Arithmetic Operators
Arithmetic operators are used to perform common mathematical operations.
| Operator |
Name |
Description |
Example |
Try it |
| + |
Addition |
Adds together two values |
x + y |
Try it » |
| - |
Subtraction |
Subtracts one value from another |
x - y |
Try it » |
| * |
Multiplication |
Multiplies two values |
x * y |
Try it » |
| / |
Division |
Divides one value by another |
x / y |
Try it » |
| % |
Modulus |
Returns the division remainder |
x % y |
Try it » |
| ++ |
Increment |
Increases the value of a variable by 1 |
++x |
Try it » |
| -- |
Decrement |
Decreases the value of a variable by 1 |
--x |
Try it » |
C++ Operators
Operators are used to perform operations on variables and values.
In the example below, we use the
+ operator to add together two values:
Example
int x = 100 + 50;
Run example »
Although The + operator is often used to add together two values, like in the example above, it can also be used to add together a variable and a value, or a variable and another variable:
Example
int sum1 = 100 + 50;
// 150 (100 + 50)
int sum2 = sum1 + 250; // 400 (150 + 250)
int sum3 = sum2 + sum2; // 800 (400 + 400)
Run example »
C++ divides the operators into the following groups:
Arithmetic Operators
Arithmetic operators are used to perform common mathematical operations.
| Operator |
Name |
Description |
Example |
Try it |
| + |
Addition |
Adds together two values |
x + y |
Try it » |
| - |
Subtraction |
Subtracts one value from another |
x - y |
Try it » |
| * |
Multiplication |
Multiplies two values |
x * y |
Try it » |
| / |
Division |
Divides one value by another |
x / y |
Try it » |
| % |
Modulus |
Returns the division remainder |
x % y |
Try it » |
| ++ |
Increment |
Increases the value of a variable by 1 |
++x |
Try it » |
| -- |
Decrement |
Decreases the value of a variable by 1 |
--x |
Try it » |
Assignment Operators
Assignment operators are used to assign values to variables.
In the example below, we use the assignment operator (
=) to assign the value 10 to a variable called x:
Example
int x = 10;
Try it Yourself »
The addition assignment operator (
+=) adds a value to a variable:
Example
int x = 10;
x += 5;
Try it Yourself »
A list of all assignment operators:
Comparison Operators
Comparison operators are used to compare two values.
Note: The return value of a comparison is either true (
1) or false (
0).
In the following example, we use the greater than operator (
>) to find out if 5 is greater than 3:
Example
int x = 5;
int y = 3;
cout << (x > y); // returns 1 (true) because 5 is greater than 3
Try it Yourself »
A list of all comparison operators:
You will learn much more about comparison operators and how to use them in a later chapter.
Logical Operators
Logical operators are used to determine the logic between variables or
values:
| Operator |
Name |
Description |
Example |
Try it |
| && |
Logical and |
Returns true if both statements are true |
x < 5 && x < 10 |
Try it » |
| || |
Logical or |
Returns true if one of the statements is true |
x < 5 || x < 4 |
Try it » |
| ! |
Logical not |
Reverse the result, returns false if the result is true |
!(x < 5 && x < 10) |
Try it » |
C++ Strings
Strings are used for storing text.
A string variable contains a collection of characters surrounded by double quotes:
string greeting = "Hello";
to use strings, you must include an additional header file in the source code, The <string> library:
Example
// Include the string library
#include <string>
// Create a string variable
string greeting = "Hello";
String Concatenation
The + operator can be used between strings to add them together to make a new
string. This is called concatenation:
string firstName = "John ";
string lastName = "Doe";
string fullName =
firstName + lastName;
cout << fullName;
In the example above, we added a space after firstName to create a space
between John and Doe on output. However, you could also add a space with quotes (
" " or
' '):
string firstName = "John";
string lastName = "Doe";
string fullName =
firstName + " " + lastName;
cout << fullName;
Append
A string in C++ is actually an object, which contain functions that can perform certain operations on strings. For example, you can also concatenate strings with The append() function:
Example
string firstName = "John ";
string lastName = "Doe";
string fullName =
firstName.append(lastName);
cout << fullName;
It is up to you whether you want to use + or append(). The major difference between the two, is that The append() function is much faster. However, for testing and such, it might be easier to just use +.
Adding Numbers and Strings
WARNING!
C++ uses The + operator for both addition and concatenation.
Numbers are added. Strings are concatenated.
If you add two numbers, the result will be a number:
int x = 10;
int y = 20;
int z = x + y; // z will be 30 (an integer)
If you add two strings, the result will be a string concatenation:
Example
string x = "10";
string y = "20";
string z = x + y; // z will be 1020 (a string)
If you try to add a number to a string, an error occurs:
Example
string x = "10";
int y = 20;
string z = x + y;
String Length
to get the length of a string, use The length() function:
Example
string txt = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
cout << "The length of the txt
string is: " << txt.length();
Run example »
Tip: You might see some C++ programs that use The size() function to get the length of a string. This is just an alias of length(). It is completely up to you if you want to use
length() or
size():
Example
string txt = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
cout << "The length of the txt
string is: " << txt.size();
Run example »
Access Strings
You can access the characters in a string by referring to its index number
inside square brackets [].
This example prints the first character in
myString:
Example
string
myString = "Hello";
cout << myString[0];
// Outputs H
Run example »
Note: String indexes start with 0: [0] is the first character. [1] is the second
character, etc.
This example prints the second character in
myString:
Example
string
myString = "Hello";
cout << myString[1];
// Outputs e
Run example »
Change String Characters
to change the value of a specific character in a string, refer to the index
number, and use single quotes:
Example
string
myString = "Hello";
myString[0] = 'J';
cout << myString;
//
Outputs Jello instead of Hello
Run example »
User Input Strings
It is possible to use the extraction operator
>> on
cin to display a string entered by a user:
Example
string firstName;
cout << "Type your first name: ";
cin >>
firstName;
// get user input from the keyboard
cout << "Your name is: " <<
firstName;
// Type your first name: John
// Your name is: John
However, cin considers a space (whitespace, tabs, etc) as a terminating
character, which means that it can only display a single word (even if you type
many words):
Example
string fullName;
cout << "Type your full name: ";
cin >>
fullName;
cout << "Your name is: " <<
fullName;
// Type your full name: John Doe
// Your name is: John
From the example above, you would expect the program to print "John Doe", but it only prints "John".
That's why, when working with strings, we often use The getline()
function to read a line of text. It takes
cin as the first parameter, and the string
variable as second:
Example
string fullName;
cout << "Type your full name: ";
getline (cin, fullName);
cout << "Your name is: " <<
fullName;
// Type your full name: John Doe
// Your name is: John Doe
Run example »
Omitting Namespace
You might see some C++ programs that runs without the standard namespace library. The using namespace std line can be omitted and replaced with The std keyword, followed by the :: operator
for
string (and cout) objects:
Example
#include <iostream>
#include <string>
int main() {
std::string greeting = "Hello";
std::cout
<< greeting;
return 0;
}
Run example »
It is up to you if you want to include the standard namespace library or not.
C++ Math
C++ has many functions that allows you to perform mathematical tasks on numbers.
Max and min
The max(x,y) function can be used to find the highest value of x and
y:
Example
cout << max(5, 10);
Run example »
And The min(x,y) function can be used to find the lowest value of x
and y:
Example
cout << min(5, 10);
Run example »
C++ <cmath> Header
Other functions, such as
sqrt (square root), round (rounds a number) and log
(natural logarithm), can be found in The <cmath> header
file:
Example
// Include the cmath library
#include <cmath>
cout <<
sqrt(64);
cout << round(2.6);
cout << log(2);
Run example »
Other Math Functions
A list of other popular Math functions (from The <cmath> library) can be found in the table below:
| Function |
Description |
| abs(x) |
Returns the absolute value of x |
| acos(x) |
Returns the arccosine of x, in radians |
| asin(x) |
Returns the arcsine of x, in radians |
| atan(x) |
Returns the arctangent of x, in radians |
| cbrt(x) |
Returns the cube root of x |
| ceil(x) |
Returns the value of x rounded up to its nearest integer |
| cos(x) |
Returns the cosine of x, in radians |
| cosh(x) |
Returns the hyperbolic cosine of x, in radians |
| exp(x) |
Returns the value of Ex |
| expm1(x) |
Returns ex -1 |
| fabs(x) |
Returns the absolute value of a floating x |
| fdim(x, y) |
Returns the positive difference between x and y |
| floor(x) |
Returns the value of x rounded down to its nearest integer |
| hypot(x, y) |
Returns sqrt(x2 +y2) without intermediate overflow or underflow |
| fma(x, y, z) |
Returns x*y+z without losing precision |
| fmax(x, y) |
Returns the highest value of a floating x and y |
| fmin(x, y) |
Returns the lowest value of a floating x and y |
| fmod(x, y) |
Returns the floating point remainder of x/y |
| pow(x, y) |
Returns the value of x to the power of y |
| sin(x) |
Returns the sine of x (x is in radians) |
| sinh(x) |
Returns the hyperbolic sine of a double value |
| tan(x) |
Returns the tangent of an angle |
| tanh(x) |
Returns the hyperbolic tangent of a double value |
C++ Booleans
Very often, in programming, you will need a data type that can only have one of two values, like:
- YES / NO
- ON / OFF
- TRUE / FALSE
For this, C++ has a bool data type, which can take the values
true
(1) or
false (0).
Boolean Values
A boolean variable is declared with The bool keyword and can only take the values
true or
false:
Example
bool isCodingFun = true;
bool isFishTasty = false;
cout << isCodingFun;
// Outputs 1 (true)
cout << isFishTasty; // Outputs 0 (false)
Run example »
From the example above, you can read that a true value returns
1, and false returns
0.
However, it is more common to return boolean values from boolean expressions
(see next page).
C++ Booleans
Very often, in programming, you will need a data type that can only have one of two values, like:
- YES / NO
- ON / OFF
- TRUE / FALSE
For this, C++ has a bool data type, which can take the values
true
(1) or
false (0).
Boolean Values
A boolean variable is declared with The bool keyword and can only take the values
true or
false:
Example
bool isCodingFun = true;
bool isFishTasty = false;
cout << isCodingFun;
// Outputs 1 (true)
cout << isFishTasty; // Outputs 0 (false)
Run example »
From the example above, you can read that a true value returns
1, and false returns
0.
However, it is more common to return boolean values from boolean expressions
(see next page).
Boolean Expression
A Boolean expression is a C++ expression that returns a boolean value:
1 (true) or
0 (false).
You can use a comparison operator, such as the greater than (
>) operator to find out if an expression (or a variable) is true:
Example
int x = 10;
int y = 9;
cout << (x > y); // returns 1 (true), because 10 is higher than 9
Run example »
Or even easier:
Example
cout << (10 > 9); // returns 1 (true), because 10 is higher than 9
Run example »
In the examples below, we use the equal to (
==) operator to evaluate an expression:
Example
int x = 10;
cout << (x == 10); // returns 1 (true), because the value
of x is equal to 10
Run example »
Example
cout << (10 == 15); // returns
0 (false), because 10 is not equal to 15
Run example »
Booleans are the basis for all C++ comparisons and conditions.
You will learn more about conditions (if...else) in the next chapter.
C++ Conditions and If Statements
C++ supports the usual logical conditions from mathematics:
- Less than: a < b
- Less than or equal to: a <= b
- Greater than: a > b
- Greater than or equal to: a >= b
- Equal to a == b
- Not Equal to: a != b
You can use these conditions to perform different actions for different decisions.
C++ has the following conditional statements:
- Use
if to specify a block of code to be executed, if a specified condition is true
- Use
else to specify a block of code to be executed, if the same condition is false
- Use
else if to specify a new condition to test, if the first condition is false
- Use
switch to specify many alternative blocks of code to be executed
The if Statement
Use The if statement to specify a block of C++ code to be executed if a condition is true.
Syntax
if (condition) {
// block of code to be executed if The condition is true
}
Note that
if is in lowercase letters. Uppercase letters (If or IF) will generate an error.
In the example below, we test two values to find out if 20 is greater than
18. If the condition is true, print some text:
Example
if (20 > 18) {
cout << "20 is greater than 18";
}
Run example »
We can also test variables:
Example
int x = 20;
int y = 18;
if (x > y) {
cout << "x is greater than
y";
}
Run example »
Example explained
In the example above we use two variables, x and y, to test whether x is greater than y
(using The > operator). As x is 20, and y is 18, and we know that 20 is greater than 18, we print to the screen that "x is greater than y".
C++ Conditions and If Statements
C++ supports the usual logical conditions from mathematics:
- Less than: a < b
- Less than or equal to: a <= b
- Greater than: a > b
- Greater than or equal to: a >= b
- Equal to a == b
- Not Equal to: a != b
You can use these conditions to perform different actions for different decisions.
C++ has the following conditional statements:
- Use
if to specify a block of code to be executed, if a specified condition is true
- Use
else to specify a block of code to be executed, if the same condition is false
- Use
else if to specify a new condition to test, if the first condition is false
- Use
switch to specify many alternative blocks of code to be executed
The if Statement
Use The if statement to specify a block of C++ code to be executed if a condition is true.
Syntax
if (condition) {
// block of code to be executed if The condition is true
}
Note that
if is in lowercase letters. Uppercase letters (If or IF) will generate an error.
In the example below, we test two values to find out if 20 is greater than
18. If the condition is true, print some text:
Example
if (20 > 18) {
cout << "20 is greater than 18";
}
Run example »
We can also test variables:
Example
int x = 20;
int y = 18;
if (x > y) {
cout << "x is greater than
y";
}
Run example »
Example explained
In the example above we use two variables, x and y, to test whether x is greater than y
(using The > operator). As x is 20, and y is 18, and we know that 20 is greater than 18, we print to the screen that "x is greater than y".
The else Statement
Use The else statement to specify a block of code to be executed if the condition is false.
Syntax
if (condition) {
// block of code to be executed if The condition is true
} else {
// block of code to be executed
if the condition is false
}
Example
int time = 20;
if (time < 18) {
cout << "Good
day.";
} else {
cout << "Good
evening.";
}
// Outputs "Good evening."
Run example »
Example explained
In the example above, time (20) is greater than 18, so the condition is false.
Because of this, we move on to The else condition and print to the screen "Good
evening". If the time was less than 18, the program would print "Good day".
The else if Statement
Use The else if statement to specify a new condition if the first condition is false.
Syntax
if (condition1) {
// block of code to be executed if
condition1 is true
} else if (condition2) {
// block of code to be executed if the condition1 is false and condition2 is true
} else {
// block of code to be executed if the condition1 is false
and condition2 is false
}
Example
int time = 22;
if (time < 10) {
cout << "Good
morning.";
} else if (time < 20) {
cout << "Good
day.";
} else {
cout << "Good evening.";
}
// Outputs "Good evening."
Run example »
Example explained
In the example above, time (22) is greater than 10, so the first condition is false. The next condition, in the
else if statement, is also
false, so we move on to The else
condition since condition1 and condition2 is both
false - and print to the screen "Good
evening".
However, if the time was 14, our program would print "Good day."
Short Hand If...Else (Ternary Operator)
There is also a short-hand if else, which is known as the ternary operator
because it consists of three operands. It can be used to replace multiple lines
of code with a single line. It is often used to replace simple if else
statements:
Syntax
variable = (condition) ? expressionTrue :
expressionFalse;
Instead of writing:
Example
int time = 20;
if (time < 18) {
cout << "Good
day.";
} else {
cout << "Good
evening.";
}
Run example »
You can simply write:
Example
int time = 20;
string result = (time < 18) ? "Good day." : "Good evening.";
cout << result;
Run example »
C++ Switch Statements
Use The switch statement to select one of many code blocks to be executed.
Syntax
switch(expression) {
case x:
// code
block
break;
case y:
// code block
break;
default:
// code block
}
This is how it works:
- The switch expression is evaluated once
- The value of the expression is compared with the values of each
case
- If there is a match, the associated block of code is executed
- The break and default keywords are optional, and will be described later in this chapter
The example below uses the weekday number to calculate the weekday name:
Example
int day = 4;
switch (day) {
case 1:
cout << "Monday";
break;
case 2:
cout << "Tuesday";
break;
case 3:
cout << "Wednesday";
break;
case
4:
cout << "Thursday";
break;
case 5:
cout << "Friday";
break;
case 6:
cout << "Saturday";
break;
case 7:
cout << "Sunday";
break;
}
// Outputs "Thursday" (day 4)
Run example »
The break Keyword
When C++ reaches a break
keyword, it breaks out of the switch block.
This will stop the execution of more code and case testing inside
the block.
When a match is found, and the job is done, it's time for a break. There is no need for more testing.
A break can save a lot of execution time because it "ignores" the execution
of all the rest of the code in the switch block.
The default Keyword
The default keyword specifies some code to run if there is no
case match:
Example
int day = 4;
switch (day) {
case 6:
cout << "Today is Saturday";
break;
case 7:
cout << "Today is Sunday";
break;
default:
cout << "Looking
forward to the Weekend";
}
// Outputs "Looking forward to the Weekend"
Run example »
Note: The default keyword must be used as the last statement
in the switch, and it does not need a break.
C++ Loops
Loops can execute a block of code as long as a specified condition is reached.
Loops are handy because they save time, reduce errors, and they make code more readable.
C++ While Loop
The while loop loops through a block of code as long as a specified condition is true:
Syntax
while (condition) {
// code block to be executed
}
In the example below, the code in the loop will run, over and over again, as long as
a variable (
i) is less than 5:
Example
int i = 0;
while (i < 5) {
cout << i << "\n";
i++;
}
Run example »
Note: Do not forget to increase the variable used in the condition, otherwise
the loop will never end!
C++ Loops
Loops can execute a block of code as long as a specified condition is reached.
Loops are handy because they save time, reduce errors, and they make code more readable.
C++ While Loop
The while loop loops through a block of code as long as a specified condition is true:
Syntax
while (condition) {
// code block to be executed
}
In the example below, the code in the loop will run, over and over again, as long as
a variable (
i) is less than 5:
Example
int i = 0;
while (i < 5) {
cout << i << "\n";
i++;
}
Run example »
Note: Do not forget to increase the variable used in the condition, otherwise
the loop will never end!
The Do/While Loop
The do/while loop is a variant of The while loop. This loop will
execute the code block once, before checking if the condition is true, then it will
repeat the loop as long as the condition is true.
Syntax
do {
// code block to be executed
}
while (condition);
The example below uses a do/while loop. The loop will always be
executed at least once, even if the condition is false, because the code block is executed before the condition is tested:
Example
int i = 0;
do {
cout << i << "\n";
i++;
}
while (i < 5);
Run example »
Do not forget to increase the variable used in the condition, otherwise
the loop will never end!
C++ For Loop
When you know exactly how many times you want to loop through a block of code, use The for loop instead of a while loop:
Syntax
for (statement 1; statement 2; statement 3) {
// code block to be executed
}
Statement 1 is executed (one time) before the execution of the code block.
Statement 2 defines the condition for executing the code block.
Statement 3 is executed (every time) after the code block has been executed.
The example below will print the numbers 0 to 4:
Example
for (int i = 0; i < 5; i++) {
cout << i << "\n";
}
Run example »
Example explained
Statement 1 sets a variable before the loop starts (int i = 0).
Statement 2 defines the condition for the loop to run (i must be less than
5). If the condition is true, the loop will start over again, if it is false, the loop will end.
Statement 3 increases a value (i++) each time the code block in the loop has
been executed.
Another Example
This example will only print even values between 0 and 10:
Example
for (int i = 0; i <= 10; i = i + 2) {
cout << i << "\n";
}
Run example »
C++ Break
You have already seen The break statement used in an earlier chapter of this tutorial. It was used to "jump out" of a switch statement.
The break statement can also be used to jump out of a loop.
This example jumps out of the loop when
i is equal to 4:
Example
for (int i = 0; i < 10; i++) {
if (i == 4) {
break;
}
cout << i << "\n";
}
Run example »
C++ Continue
The continue statement breaks one iteration (in the loop), if a specified condition occurs, and continues with the next iteration in the loop.
This example skips the value of 4:
Example
for (int i = 0; i < 10; i++) {
if (i == 4) {
continue;
}
cout << i << "\n";
}
Run example »
Break and Continue in While Loop
You can also use
break and continue in while loops:
Break Example
int i = 0;
while (i < 10) {
cout << i << "\n";
i++;
if (i == 4) {
break;
}
}
Run example »
Continue Example
int i = 0;
while (i < 10) {
if (i == 4) {
i++;
continue;
}
cout << i << "\n";
i++;
}
Run example »
C++ Arrays
Arrays are used to store multiple values in a single variable, instead of declaring separate variables for each
value.
to declare an array, define the variable type, specify the name
of the array followed by square brackets
and specify the number of elements it should store:
string cars[4];
We have now declared a variable that holds an array of four strings. To insert
values to it, we can use an array literal - place the values in a comma-separated list, inside curly braces:
string cars[4] = {"Volvo", "BMW", "Ford", "Mazda"};
to create an array of three integers, you could write:
int myNum[3] = {10, 20, 30};
Access the Elements of an Array
You access an array element by referring to the index number.
This statement accesses the value of the first element in
cars:
Example
string cars[4] = {"Volvo", "BMW", "Ford", "Mazda"};
cout << cars[0];
// Outputs Volvo
Run example »
Note: Array indexes start with 0: [0] is the first element. [1] is the second
element, etc.
Change an Array Element
to change the value of a specific element, refer to the index number:
Example
cars[0] = "Opel";
Example
string cars[4] = {"Volvo", "BMW", "Ford", "Mazda"};
cars[0] = "Opel";
cout << cars[0];
// Now outputs Opel instead of Volvo
Run example »
C++ Arrays
Arrays are used to store multiple values in a single variable, instead of declaring separate variables for each
value.
to declare an array, define the variable type, specify the name
of the array followed by square brackets
and specify the number of elements it should store:
string cars[4];
We have now declared a variable that holds an array of four strings. To insert
values to it, we can use an array literal - place the values in a comma-separated list, inside curly braces:
string cars[4] = {"Volvo", "BMW", "Ford", "Mazda"};
to create an array of three integers, you could write:
int myNum[3] = {10, 20, 30};
Access the Elements of an Array
You access an array element by referring to the index number.
This statement accesses the value of the first element in
cars:
Example
string cars[4] = {"Volvo", "BMW", "Ford", "Mazda"};
cout << cars[0];
// Outputs Volvo
Run example »
Note: Array indexes start with 0: [0] is the first element. [1] is the second
element, etc.
Change an Array Element
to change the value of a specific element, refer to the index number:
Example
cars[0] = "Opel";
Example
string cars[4] = {"Volvo", "BMW", "Ford", "Mazda"};
cars[0] = "Opel";
cout << cars[0];
// Now outputs Opel instead of Volvo
Run example »
Loop Through an Array
You can loop through the array elements with The for
loop.
The following example outputs all elements in the cars
array:
Example
string cars[4] = {"Volvo", "BMW", "Ford", "Mazda"};
for(int i = 0; i < 4;
i++) {
cout << cars[i] << "\n";
}
Run example »
The following example outputs the index of each element together with its value:
Example
string cars[4] = {"Volvo", "BMW", "Ford", "Mazda"};
for(int i = 0; i < 4;
i++) {
cout << i << ": " << cars[i] << "\n";
}
Run example »
Omit Array Size
You don't have to specify the size of the array. But if you don't, it will
only be as big as The elements that are inserted into it:
string cars[] = {"Volvo", "BMW", "Ford"}; //
size of array is always 3
This is completely fine. However, the problem arise if you want extra space
for future elements.
Then you have to overwrite the existing values:
string cars[] = {"Volvo", "BMW", "Ford"};
string cars[] = {"Volvo", "BMW", "Ford", "Mazda", "Tesla"};
If you specify the size however, the array will reserve the extra space:
string cars[5] = {"Volvo", "BMW", "Ford"}; //
size of array is 5, even though it's only three elements inside it
Now you can add a fourth and fifth element without overwriting the others:
cars[3] = {"Mazda"};
cars[4] = {"Tesla"};
Run example »
Omit Elements on Declaration
It is also possible to declare an array without specifying the elements on declaration, and add them later:
string cars[5];
cars[0] = {"Volvo"};
cars[1] = {"BMW"};
...
Run example »
Creating References
A reference variable is a "reference" to an existing variable, and it is created with The & operator:
string food = "Pizza"; // food variable
string &meal = food;
// reference to food
Now, we can use either the variable name
food or the reference name
meal to refer to The food variable:
Example
string food = "Pizza";
string &meal = food;
cout << food << "\n";
// Outputs Pizza
cout << meal << "\n"; //
Outputs Pizza
Run example »
Creating References
A reference variable is a "reference" to an existing variable, and it is created with The & operator:
string food = "Pizza"; // food variable
string &meal = food;
// reference to food
Now, we can use either the variable name
food or the reference name
meal to refer to The food variable:
Example
string food = "Pizza";
string &meal = food;
cout << food << "\n";
// Outputs Pizza
cout << meal << "\n"; //
Outputs Pizza
Run example »
Memory Address
In the example from the previous page, The & operator was used to create a reference variable.
But it can also be used to get the memory address of a variable; which is The location of where the variable is stored on the computer.
When a variable is created in C++, a memory address is assigned to the variable.
And when we assign a value to the variable, it is stored in this memory
address.
to access it, use The &
operator, and the result will represent where the variable is stored:
Example
string food = "Pizza";
cout << &food; // Outputs 0x6dfed4
Run example »
Note: The memory address is in hexadecimal form (0x..). Note
that
you may not get the same result in your program.
And why is it useful to know the memory address?
References and Pointers (which you will learn about in the next chapter) are important in C++, because they give you The ability to manipulate the data in the computer's memory - which can reduce the code and improve the perfomance.
These two features are one of the things that make C++ stand out from other
programming languages, like Python and Java.
Creating Pointers
You learned from the previous chapter, that we can get the memory
address of a variable by using The &
operator:
Example
string food = "Pizza";
// A food variable of type string
cout <<
food; // Outputs the value of food (Pizza)
cout << &food; // Outputs the memory address of food (0x6dfed4)
Run example »
A pointer however, is a variable that stores the memory address as its value.
A pointer variable points to a data type (like
int or
string) of the same
type, and is created with The * operator. The address of the variable you're working with is assigned to the pointer:
Example
string food = "Pizza"; // A food variable
of type string
string* ptr =
&food; // A pointer variable, with the name
ptr, that stores The address of food
// Output the value of food (Pizza)
cout << food << "\n";
// Output
the memory address of food (0x6dfed4)
cout << &food << "\n";
//
Output the memory address of food with the pointer (0x6dfed4)
cout <<
ptr << "\n";
Run example »
Example explained
Create a pointer variable with the name
ptr, that points to a string variable, by using The asterisk sign
* (
string* ptr).
Note that the type of the pointer has to match the type of the variable you're
working with.
Use The & operator to store the memory address of The variable called
food, and assign it to the pointer.
Now, ptr holds the value of food's memory address.
Tip: There are three ways to declare pointer variables, but the first way is preferred:
string* mystring; // Preferred
string *mystring;
string * mystring;
Creating Pointers
You learned from the previous chapter, that we can get the memory
address of a variable by using The &
operator:
Example
string food = "Pizza";
// A food variable of type string
cout <<
food; // Outputs the value of food (Pizza)
cout << &food; // Outputs the memory address of food (0x6dfed4)
Run example »
A pointer however, is a variable that stores the memory address as its value.
A pointer variable points to a data type (like
int or
string) of the same
type, and is created with The * operator. The address of the variable you're working with is assigned to the pointer:
Example
string food = "Pizza"; // A food variable
of type string
string* ptr =
&food; // A pointer variable, with the name
ptr, that stores The address of food
// Output the value of food (Pizza)
cout << food << "\n";
// Output
the memory address of food (0x6dfed4)
cout << &food << "\n";
//
Output the memory address of food with the pointer (0x6dfed4)
cout <<
ptr << "\n";
Run example »
Example explained
Create a pointer variable with the name
ptr, that points to a string variable, by using The asterisk sign
* (
string* ptr).
Note that the type of the pointer has to match the type of the variable you're
working with.
Use The & operator to store the memory address of The variable called
food, and assign it to the pointer.
Now, ptr holds the value of food's memory address.
Tip: There are three ways to declare pointer variables, but the first way is preferred:
string* mystring; // Preferred
string *mystring;
string * mystring;
Get Memory Address and Value
In the example from the previous page, we used the pointer variable to get the memory address of a variable
(used together with The & reference operator). However, you can also
use the pointer to get the value of the variable, by using The * operator
(the dereference operator):
Example
string food = "Pizza"; // Variable declaration
string* ptr =
&food; // Pointer declaration
//
Reference: Output the memory address of food with the pointer (0x6dfed4)
cout <<
ptr << "\n";
//
Dereference: Output the value of food with the pointer (Pizza)
cout <<
*ptr << "\n";
Run example »
Note that The * sign can be confusing here, as it does two different things
in our code:
- When used in declaration (string* ptr), it creates a pointer variable.
- When not used in declaration, it act as a dereference operator.
Modify the Pointer Value
You can also change the pointer's value. But note that this will also change
the value of the original variable:
Example
string food = "Pizza";
string* ptr = &food;
// Output the value
of food (Pizza)
cout << food << "\n";
// Output the memory address
of food (0x6dfed4)
cout << &food << "\n";
// Access the memory
address of food and output its value (Pizza)
cout << *ptr << "\n";
// Change the value of the pointer
*ptr = "Hamburger";
//
Output the new value of the pointer (Hamburger)
cout << *ptr << "\n";
//
Output the new value of the food variable (Hamburger)
cout << food << "\n";
Run example »
A function is a block of code which only runs when it is called.
You can pass data, known as parameters, into a function.
Functions are used to perform certain actions, and they are
important for reusing code: Define the code once, and use it many times.
Create a Function
C++ provides some pre-defined
functions, such as
main(), which is used to execute code. But you can also
create your own functions to perform certain actions.
to create (often referred to as declare) a function, specify the name of the function, followed by parentheses ():
Syntax
void myFunction() {
// code to be executed
}
Example Explained
- myFunction() is the name of the function
- void means that the function does not have a return value. You will learn more about return values later in the next chapter
- inside the function (the body), add code that defines what the function should do
Call a Function
Declared functions are not executed immediately. They are "saved for later
use", and will be executed later, when they are called.
to call a function, write the function's name followed by two parentheses
()
and a semicolon
;
In the following example, myFunction() is used to print a text (the action), when it is called:
Example
Inside
main, call
myFunction():
// Create a function
void myFunction() {
cout << "I just got executed!";
}
int main() {
myFunction(); // call the function
return 0;
}
// Outputs
"I just got executed!"
Run example »
A function can be called multiple times:
Example
void myFunction() {
cout << "I just got executed!\n";
}
int main() {
myFunction();
myFunction();
myFunction();
return 0;
}
//
I just got executed!
// I just got executed!
// I just got executed!
Run example »
Function Declaration and Definition
A C++ function consist of two parts:
- Declaration: the function's name, return type, and parameters (if any)
- Definition: the body of the function (code to be executed)
void myFunction() { // declaration
//
the body of the function (definition)
}
Note: If a user-defined function, such as
myFunction() is declared after The main() function, an error will occur. It is because C++ works from top to bottom; which means that if the function is not declared above
main(), the program is unaware of it:
Example
int main() {
myFunction();
return 0;
}
void myFunction() {
cout << "I just got executed!";
}
// Error
Run example »
However, it is possible to separate the declaration and the definition of the function - for code optimization.
You will often see C++ programs that have function declaration above
main(), and function definition below
main(). This will make the code
better organized and easier to read:
Example
// Function declaration
void myFunction();
// The main method
int main() {
myFunction(); // call the function
return 0;
}
// Function definition
void myFunction() {
cout << "I just got executed!";
}
Run example »
Parameters and Arguments
Information can be passed to functions as a parameter. Parameters act as
variables inside the function.
Parameters are specified after the function name, inside the parentheses.
You can add as many parameters as you want, just separate them with a comma:
Syntax
void functionName(parameter1, parameter2, parameter3) {
// code to be executed
}
The following example has a function that takes a string called fname as parameter.
When the function is called, we pass along a first name,
which is used inside the function to print the full name:
Example
void myFunction(string fname) {
cout << fname << " Refsnes\n";
}
int main() {
myFunction("Liam");
myFunction("Jenny");
myFunction("Anja");
return 0;
}
// Liam Refsnes
// Jenny Refsnes
//
Anja Refsnes
Run example »
When a parameter is passed to the function, it is called an argument. So, from the example above:
fname is a parameter, while
Liam, Jenny and Anja are arguments.
Parameters and Arguments
Information can be passed to functions as a parameter. Parameters act as
variables inside the function.
Parameters are specified after the function name, inside the parentheses.
You can add as many parameters as you want, just separate them with a comma:
Syntax
void functionName(parameter1, parameter2, parameter3) {
// code to be executed
}
The following example has a function that takes a string called fname as parameter.
When the function is called, we pass along a first name,
which is used inside the function to print the full name:
Example
void myFunction(string fname) {
cout << fname << " Refsnes\n";
}
int main() {
myFunction("Liam");
myFunction("Jenny");
myFunction("Anja");
return 0;
}
// Liam Refsnes
// Jenny Refsnes
//
Anja Refsnes
Run example »
When a parameter is passed to the function, it is called an argument. So, from the example above:
fname is a parameter, while
Liam, Jenny and Anja are arguments.
Default Parameter Value
You can also use a default parameter value, by using the equals sign (
=).
If we call the function without an argument, it uses the default value ("Norway"):
Example
void myFunction(string country = "Norway") {
cout
<< country << "\n";
}
int main() {
myFunction("Sweden");
myFunction("India");
myFunction();
myFunction("USA");
return 0;
}
// Sweden
//
India
// Norway
// USA
Run example »
A parameter with a default value, is often known as an "optional parameter". From the example above,
country is an optional parameter and "Norway" is the default value.
Multiple Parameters
Inside the function, you can add as many parameters as you want:
Example
void myFunction(string fname, int age) {
cout << fname << " Refsnes.
" << age << " years old. \n";
}
int main() {
myFunction("Liam", 3);
myFunction("Jenny", 14);
myFunction("Anja", 30);
return 0;
}
// Liam Refsnes. 3 years old.
// Jenny Refsnes. 14 years old.
// Anja Refsnes. 30 years old.
Run example »
Note that when you are working with multiple parameters, the function call must
have the same number of arguments as there are parameters, and the arguments must be passed in the same order.
Return Values
The void keyword, used in the previous examples, indicates that The function should not return a value. If you
want the function to return a value, you can use a data type (such as
int,
string, etc.) instead of void, and use The return
keyword inside the function:
Example
int myFunction(int x) {
return 5
+ x;
}
int main() {
cout << myFunction(3);
return 0;
}
// Outputs
8 (5 + 3)
Run example »
This example returns the sum of a function with two parameters:
Example
int myFunction(int x, int y) {
return x + y;
}
int main()
{
cout << myFunction(5, 3);
return 0;
}
// Outputs 8 (5 + 3)
Run example »
You can also store the result in a variable:
Example
int myFunction(int x, int y) {
return x + y;
}
int main() {
int z = myFunction(5, 3);
cout << z;
return 0;
}
// Outputs 8 (5 + 3)
Run example »
Pass By Reference
In the examples from the previous page, we used normal variables when we passed parameters to a function. You can also pass a reference to the function. This can be useful when you need to change the value of the arguments:
Example
void swapNums(int &x, int &y) {
int z = x;
x = y;
y = z;
}
int main() {
int firstNum = 10;
int secondNum = 20;
cout <<
"Before swap: " << "\n";
cout << firstNum << secondNum << "\n";
// Call the function, which will change the values of firstNum
and secondNum
swapNums(firstNum, secondNum);
cout << "After swap:
" << "\n";
cout << firstNum << secondNum << "\n";
return 0;
}
Run example »
Function Overloading
With function overloading, multiple functions can have the same name with different
parameters:
Example
int myFunction(int x)
float myFunction(float x)
double
myFunction(double x, double y)
Consider the following example, which have two functions that add numbers of different type:
Example
int plusFuncInt(int x, int y) {
return x + y;
}
double plusFuncDouble(double x, double y) {
return x + y;
}
int main() {
int myNum1 = plusFuncInt(8, 5);
double myNum2 = plusFuncDouble(4.3, 6.26);
cout <<
"Int: " << myNum1 << "\n";
cout << "Double: " << myNum2;
return 0;
}
Run example »
Instead of defining two functions that should do the same thing, it is better to overload one.
In the example below, we overload The plusFunc function to work for both
int
and double:
Example
int plusFunc(int x, int
y) {
return x + y;
}
double plusFunc(double x, double y) {
return x + y;
}
int main() {
int myNum1 = plusFunc(8, 5);
double myNum2 = plusFunc(4.3, 6.26);
cout << "Int: " <<
myNum1 << "\n";
cout << "Double: " << myNum2;
return 0;
}
Run example »
Note: Multiple functions can have the same name
as long as the number and/or type of parameters are different.
C++ What is OOP?
OOP stands for Object-Oriented Programming.
Procedural programming is about writing procedures or functions that perform
operations on the data, while object-oriented programming is about
creating objects that contain both data and functions.
Object-oriented programming has several advantages over procedural
programming:
- OOP is faster and easier to execute
- OOP provides a clear structure for the programs
- OOP helps to keep the C++ code DRY "Don't Repeat Yourself", and makes
The code easier to maintain, modify and debug
- OOP makes it possible to create full reusable
applications with less code and shorter development time
Tip: The "Don't Repeat Yourself" (DRY) principle is about
reducing the repetition of code. You should extract out the codes that are
common for the application, and place them at a single place and reuse them
instead of repeating it.
C++ What are Classes and Objects?
Classes and objects are the two main aspects of object-oriented programming.
Look at the following illustration to see the difference between class and objects:
class
Fruit
objects
Apple
Banana
Mango
Another example:
class
Car
objects
Volvo
Audi
Toyota
So, a class is a template for objects, and an object is an instance of a class.
When the individual objects are created, they inherit all The variables and functions from the class.
You will learn much more about classes and objects in the next chapter.
C++ Classes/Objects
C++ is an object-oriented programming language.
Everything in C++ is associated with classes and objects, along with its attributes and methods. For example: in real life, a car is an object. The car has attributes, such as weight and color, and
methods, such as drive and brake.
Attributes and methods are basically variables and
functions that belongs to the class. These are often referred to as
"class members".
A class is a user-defined data type that we can use in our program, and it
works as an object constructor, or a "blueprint" for creating objects.
Create a Class
to create a class, use The class keyword:
Example
Create a class called "
MyClass":
class MyClass {
// The class
public:
// Access specifier
int myNum; //
Attribute (int variable)
string myString; //
Attribute (string variable)
};
Example explained
- The class keyword is used to create a class called
MyClass.
- The public keyword is an access specifier, which specifies that members (attributes and methods) of the class are accessible from outside the class. You will learn more about access specifiers later.
- Inside the class, there is an integer variable
myNum and a string variable
myString. When variables are declared
within a class, they are called attributes.
- At last, end the class definition with a semicolon
;.
Create an Object
In C++, an object is created from a class. We have already created the class named
MyClass, so now we can use this to create objects.
to create an object of MyClass, specify The class name, followed by the object name.
to access the class attributes (
myNum and myString), use the dot syntax (
.)
on the object:
Example
Create an object called "
myObj" and access
the attributes:
class MyClass { // The class
public:
// Access specifier
int myNum; //
Attribute (int variable)
string myString; //
Attribute (string variable)
};
int main() {
MyClass myObj;
// Create an object of MyClass
// Access attributes and set values
myObj.myNum
= 15;
myObj.myString = "Some text";
// Print attribute values
cout << myObj.myNum << "\n";
cout << myObj.myString;
return 0;
}
Run example »
Multiple Objects
You can create multiple objects of one class:
Example
// Create a Car class with some attributes
class Car {
public:
string brand;
string model;
int
year;
};
int main() {
// Create an object of Car
Car carObj1;
carObj1.brand = "BMW";
carObj1.model = "X5";
carObj1.year = 1999;
// Create another object of Car
Car
carObj2;
carObj2.brand = "Ford";
carObj2.model =
"Mustang";
carObj2.year = 1969;
// Print
attribute values
cout << carObj1.brand << " " << carObj1.model << " " << carObj1.year << "\n";
cout <<
carObj2.brand << " " << carObj2.model << " " << carObj2.year << "\n";
return 0;
}
Run example »
Class Methods
Methods are functions that belongs to the class.
There are two ways to define functions that belongs to a class:
- Inside class definition
- Outside class definition
In the following example, we define a function inside the class, and we name
it "myMethod".
Note: You access methods just like you access attributes; by creating an object of the class and by using the dot syntax (.):
Inside Example
class MyClass { // The classpublic:
// Access specifier
void myMethod() { // Method/function
defined inside The class
cout << "Hello World!";
}
};
int main() {
MyClass
myObj; // Create an object of MyClass
myObj.myMethod(); // Call the method
return 0;
}
Run example »
to define a function outside the class definition, you have to declare it
inside the class and then define it outside of the class. This is done by specifiying The name of the class, followed the scope resolution
:: operator, followed by the name of the function:
Outside Example
class MyClass { // The class
public:
// Access specifier
void myMethod(); // Method/function
declaration
};
// Method/function definition outside the class
void
MyClass::myMethod() {
cout << "Hello World!";
}
int main() {
MyClass
myObj; // Create an object of MyClass
myObj.myMethod(); // Call the method
return 0;
}
Run example »
Parameters
You can also add parameters:
Example
#include <iostream>
using namespace std;
class Car {
public:
int speed(int maxSpeed);
};
int Car::speed(int maxSpeed) {
return maxSpeed;
}
int main() {
Car myObj; // Create an object of Car
cout << myObj.speed(200); //
Call the method with an argument
return 0;
}
Run example »
Constructors
A constructor in C++ is a special method that is automatically called when an object of a class is created.
to create a constructor, use the same name as the class, followed by
parentheses
():
Example
class MyClass { // The class
public:
// Access specifier
MyClass() {
// Constructor
cout << "Hello World!";
}
};
int main() {
MyClass myObj; // Create an object of MyClass (this will call
the constructor)
return 0;
}
Run example »
Note: The constructor has the same name as the class, it is always
public, and it does not have any return value.
Constructor Parameters
Constructors can also take parameters (just like regular functions), which can be
useful for setting initial values for attributes.
The following class have
brand, model and year attributes, and a constructor with
different parameters. Inside the constructor we set the attributes equal to The constructor parameters (
brand=x, etc). When we call the constructor
(by creating an object of the class), we pass parameters to the constructor, which will set the value of the corresponding attributes to the same:
Example
class Car { // The class
public: // Access specifier
string brand; // Attribute
string model; // Attribute
int year; // Attribute
Car(string x, string y, int z)
{ // Constructor with parameters
brand =
x;
model = y;
year = z;
}
};
int main() {
//
Create Car objects and call the constructor with different values
Car carObj1("BMW", "X5", 1999);
Car carObj2("Ford", "Mustang", 1969);
// Print values
cout << carObj1.brand << " "
<< carObj1.model << " " << carObj1.year << "\n";
cout <<
carObj2.brand << " " << carObj2.model << " " << carObj2.year << "\n";
return 0;
}
Run example »
Just like functions, constructors can also be defined outside the class.
First, declare the constructor inside the class, and then define it outside of The class by specifying the name of the class, followed by the scope resolution
::
operator, followed by the name of the constructor (which is the same as The class):
Example
class Car { // The class
public: // Access
specifier
string brand; // Attribute
string model; // Attribute
int year;
// Attribute
Car(string x, string y, int z); //
Constructor declaration
};
// Constructor definition outside The class
Car::Car(string x, string y, int z) {
brand = x;
model = y;
year = z;
}
int main() {
// Create
Car objects and call the constructor with different values
Car
carObj1("BMW", "X5", 1999);
Car carObj2("Ford", "Mustang", 1969);
// Print values
cout << carObj1.brand << " " <<
carObj1.model << " " << carObj1.year << "\n";
cout <<
carObj2.brand << " " << carObj2.model << " " << carObj2.year << "\n";
return 0;
}
Run example »
Access Specifiers
By now, you are quite familiar with The public keyword that appears in all of our class examples:
Example
class MyClass { // The class
public: // Access specifier
// class members goes here
};
Run example »
The public keyword is an access specifier.
Access specifiers define how the members (attributes and methods) of a class can
be accessed. In the example above, the members are
public - which means that they
can be accessed and modified from outside the code.
However, what if we want
members to be private and hidden from the outside world?
In C++, there are three access specifiers:
- public - members are accessible from outside the class
- private - members cannot be accessed (or
viewed) from outside the class
- protected - members cannot be accessed from
outside the class, however, they can be accessed in inherited classes. You will learn more about Inheritance later.
In the following example, we demonstrate the differences between
public and private members:
Example
class
MyClass {
public: // Public access
specifier
int x; // Public attribute
private: // Private access specifier
int y; // Private attribute
};
int main() {
MyClass
myObj;
myObj.x = 25; // Allowed (public)
myObj.y = 50; //
Not allowed (private)
return 0;
}
If you try to access a private member, an error occurs:
error: y is private
Run example »
Note: It is possible to access private members of a class
using a public method inside the same class. See the next chapter (Encapsulation)
on how to do this.
Tip: It is considered good practice to declare your class attributes as private (as
often as you can). This will reduce the possibility of yourself (or others) to mess up the code. This is also The main ingredient of the Encapsulation
concept, which you will learn more about in the next chapter.
Note: By default, all members of a class are
private if you don't specify an access specifier:
Example
class
MyClass {
int x; // Private attribute
int y; // Private attribute
};
Encapsulation
The meaning of Encapsulation, is to make sure that
"sensitive" data is hidden from users. To achieve this, you must declare class variables/attributes as
private (cannot
be accessed from outside the class). If you want others to read or modify The value of a private member, you can provide public get and set methods.
Access Private Members
to access a private attribute, use public "get" and "set" methods:
Example
#include <iostream>
using namespace std;
class Employee {
private:
// Private attribute
int salary;
public:
// Setter
void setSalary(int s) {
salary = s;
}
// Getter
int getSalary() {
return salary;
}
};
int
main() {
Employee myObj;
myObj.setSalary(50000);
cout << myObj.getSalary();
return 0;
}
Run example »
Example explained
The salary attribute is private, which have restricted access.
The public
setSalary() method takes a parameter (
s) and assigns it to the
salary attribute (salary = s).
The public
getSalary() method returns the value of the private
salary attribute.
Inside
main(), we create an object of The Employee class. Now we can use The
setSalary() method to set the value of The private attribute to 50000. Then we call The
getSalary() method on the object to return the value.
Why Encapsulation?
- It is considered good practice to declare your class attributes as private (as
often as you can). Encapsulation ensures better control of your data, because you (or others) can change one part of the code without affecting other parts
- Increased security of data
Inheritance
In C++, it is possible to inherit attributes and methods from one class to another. We group the "inheritance concept" into two categories:
- derived class (child) - the class that inherits from another class
- base class (parent) - the class being inherited from
to inherit from a class, use The : symbol.
In the example below, The Car class
(child) inherits the attributes and methods from The Vehicle class
(parent):
Example
// Base class
class Vehicle {
public:
string brand = "Ford";
void honk() {
cout << "Tuut, tuut! \n" ;
}
};
// Derived
class
class Car: public Vehicle {
public:
string model = "Mustang";
};
int main() {
Car myCar;
myCar.honk();
cout << myCar.brand + " " + myCar.model;
return 0;
}
Run example »
Why And When To Use "Inheritance"?
- It is useful for code reusability: reuse attributes and methods of an existing class when you create a new class.
Inheritance
In C++, it is possible to inherit attributes and methods from one class to another. We group the "inheritance concept" into two categories:
- derived class (child) - the class that inherits from another class
- base class (parent) - the class being inherited from
to inherit from a class, use The : symbol.
In the example below, The Car class
(child) inherits the attributes and methods from The Vehicle class
(parent):
Example
// Base class
class Vehicle {
public:
string brand = "Ford";
void honk() {
cout << "Tuut, tuut! \n" ;
}
};
// Derived
class
class Car: public Vehicle {
public:
string model = "Mustang";
};
int main() {
Car myCar;
myCar.honk();
cout << myCar.brand + " " + myCar.model;
return 0;
}
Run example »
Why And When To Use "Inheritance"?
- It is useful for code reusability: reuse attributes and methods of an existing class when you create a new class.
Multilevel Inheritance
A class can also be derived from one class, which is already derived from
another class.
In the following example, MyGrandChild is derived from class
MyChild (which is derived
from
MyClass).
Example
// Base class (parent)
class MyClass {
public:
void
myFunction() {
cout << "Some content in parent class." ;
}
};
//
Derived
class (child)
class MyChild: public MyClass {
};
// Derived class
(grandchild)
class MyGrandChild: public MyChild {
};
int main() {
MyGrandChild myObj;
myObj.myFunction();
return 0;
}
Run example »
Multiple Inheritance
A class can also be derived from more than one base class, using a comma-separated list:
Example
// Base class
class MyClass {
public:
void
myFunction() {
cout << "Some content in parent class." ;
}
};
//
Another base class
class MyOtherClass {
public:
void
myOtherFunction() {
cout << "Some content in another class." ;
}
};
//
Derived
class
class MyChildClass: public MyClass, public MyOtherClass {
};
int main() {
MyChildClass myObj;
myObj.myFunction();
myObj.myOtherFunction();
return 0;
}
Run example »
Access Specifiers
You learned from the Access Specifiers chapter that there are three
specifiers available in C++. Until now, we have only used
public (members of a class are accessible from outside the class) and private (members can only be
accessed within the class). The third specifier, protected, is similar to
private, but it can also be accessed in The inherited class:
Example
// Base class
class
Employee {
protected: // Protected access specifier
int salary;
};
// Derived class
class Programmer: public Employee {
public:
int bonus;
void
setSalary(int s) {
salary = s;
}
int getSalary() {
return salary;
}
};
int main() {
Programmer myObj;
myObj.setSalary(50000);
myObj.bonus =
15000;
cout <<
"Salary: " << myObj.getSalary() << "\n";
cout << "Bonus: " <<
myObj.bonus << "\n";
return 0;
}
Run example »
Polymorphism
Polymorphism means "many forms", and it occurs when we have many classes that are related to each other by inheritance.
Like we specified in the previous chapter;
Inheritance lets us
inherit attributes and methods from another class. Polymorphism
uses those methods to perform different tasks. This allows us to perform a single
action in different ways.
For example, think of a base class called
Animal that has a method called
animalSound(). Derived classes of Animals could be Pigs, Cats, Dogs, Birds - And they also have their own implementation of an animal sound (the pig oinks, and the cat meows, etc.):
Example
// Base class
class Animal {
public:
void
animalSound() {
cout << "The animal makes a sound \n"
;
}
};
// Derived class
class Pig : public Animal {
public:
void
animalSound() {
cout << "The pig says: wee wee \n" ;
}
};
// Derived class
class Dog
: public Animal {
public:
void animalSound()
{
cout << "The dog says: bow wow \n" ;
}
};
Remember from the Inheritance chapter that we use The : symbol to inherit from a class.
Now we can create
Pig and
Dog objects and override The animalSound() method:
Example
// Base class
class Animal {
public:
void
animalSound() {
cout << "The animal makes a sound \n"
;
}
};
// Derived class
class Pig : public Animal {
public:
void
animalSound() {
cout << "The pig says: wee wee \n" ;
}
};
// Derived class
class Dog
: public Animal {
public:
void animalSound()
{
cout << "The dog says: bow wow \n" ;
}
};
int main() {
Animal
myAnimal;
Pig myPig;
Dog myDog;
myAnimal.animalSound();
myPig.animalSound();
myDog.animalSound();
return 0;
}
Run example »
Why And When To Use "Inheritance" and "Polymorphism"?
- It is useful for code reusability: reuse attributes and methods of an existing class when you create a new class.
C++ Files
The fstream library allows us to work with files.
to use The fstream library, include both the standard
<iostream> AND The <fstream> header file:
Example
#include <iostream>
#include <fstream>
There are three objects included in The fstream library, which are used to create, write or read files:
| Object/Data Type |
Description |
|
ofstream |
Creates and writes to files |
|
ifstream |
Reads from files |
|
fstream |
A combination of ofstream and ifstream: creates, reads, and writes to files |
Create and Write To a File
to create a file, use either The ofstream or
fstream object, and specify the name of the file.
to write to the file, use the insertion operator (
<<).
Example
#include <iostream>
#include <fstream>
using namespace std;
int main() {
// Create and open a text file
ofstream MyFile("filename.txt");
//
Write to the file
MyFile << "Files can be tricky, but it is fun
enough!";
//
Close the file
MyFile.close();
}
Why do we close the file?
It is considered good practice, and it can clean up unnecessary memory space.
Read a File
to read from a file, use either The ifstream or fstream object, and the name of the file.
Note that we also use a while loop together with The getline() function (which belongs to The ifstream object) to read the file line by line, and to print the content of the file:
Example
// Create a text string, which is used to output the text file
string myText;
// Read from the text file
ifstream MyReadFile("filename.txt");
// Use a while loop together with the getline() function to read the file line by line
while (getline (MyReadFile, myText)) {
// Output the text from the file
cout << myText;
}
// Close the file
MyReadFile.close();
C++ Exceptions
When executing C++ code, different errors can occur: coding errors made by the programmer, errors due to wrong input, or other unforeseeable things.
When an error occurs, C++ will normally stop and generate an error message. The technical term for this is: C++ will throw an exception (throw an error).
C++ try and catch
Exception handling in C++ consist of three keywords:
try, throw and catch:
The try statement allows you to define a block of code to be
tested for errors while it is being executed.
The throw keyword throws an exception when a problem is detected, which lets us create a custom error.
The catch statement allows you to define a block of code to be executed, if an error occurs in the try block.
The try and catch keywords
come in pairs:
Example
try {
// Block of code to try
throw exception;
// Throw an exception when a problem arise
}
catch () {
// Block of code to handle errors
}
Consider the following example:
Example
try {
int age = 15;
if (age > 18) {
cout << "Access granted - you are old enough.";
} else {
throw (age);
}
}
catch (int
myNum) {
cout << "Access denied - You must be at least 18 years
old.\n";
cout << "Age is: " << myNum;
}
Run example »
Example explained
We use The try block to test some code: If The age variable is less than
18, we will
throw an exception, and handle it in our
catch block.
In The catch block, we catch the error and do something about it. The catch
statement takes a parameter: in our example we use an int variable (
myNum) (because we are throwing an exception of int type in The try block (
age)), to output the value of age.
If no error occurs (e.g. if
age is 20 instead of 15, meaning it will be be greater
than 18), The catch block is skipped:
Example
int age = 20;
Run example »
You can also use The throw keyword to output a reference number, like a custom error number/code for organizing purposes:
Example
try {
int age = 15;
if (age > 18) {
cout << "Access granted - you are old enough.";
} else {
throw 505;
}
}
catch (int myNum) {
cout << "Access denied - You must be at least 18 years old.\n";
cout << "Error number: " << myNum;
}
Run example »
Handle Any Type of Exceptions (...)
If you do not know The throw type used in The try block, you can use the "three dots" syntax (
...) inside The catch block, which will handle any type of exception:
Example
try {
int age = 15;
if (age > 18) {
cout << "Access granted - you are old enough.";
} else {
throw 505;
}
}
catch (...) {
cout << "Access denied - You must be at least 18 years
old.\n";
}
Run example »
Add Two Numbers
Learn how to add two numbers in C++:
Example
int x = 5;
int y = 6;
int sum = x + y;
cout << sum;
Run example »
Add Two Numbers with User Input
In this example, the user must input two numbers. Then we print The sum by calculating (adding) the two numbers:
Example
int x, y;
int sum;
cout << "Type a number: ";
cin >> x;
cout << "Type another number: ";
cin >>
y;
sum = x + y;
cout << "Sum is: " << sum;
Run example »
C++ Tutorial for Beginners - Full Course
C++ Tutorial for Beginners - Full Course
What is C++, Its Introduction and History | CPP Programming Video Tutorial
Where CPP is Used, Why Learn C++ Programming Language | Video Tutorial
C++ Source Code to Executable | Compilation, Linking, Pre Processing | Build Process Explained
Tool Set, Tool Chain and IDE | C++ Programming Video Tutorial
Installing Code Blocks IDE with Compiler for C and C++
C++ First Hello World Program | CPP Programming Video Tutorial
C++ Constants, Variables, Data types, Keywords | C++ Programming Video Tutorial
Creating and Using C++ Variables | CPP Programming Video Tutorial
C++ Console Output with Cout | CPP Programming Tutorial
Cin in C++ for Receiving User, Console Input | CPP Programming Video Tutorial
C++ Comments | CPP Programming Video Tutorials
C++ Arithmetic Operators | CPP Programming Video Tutorials
C++ Increment and Decrement Operators | CPP Programming Video Tutorial
C++ Modulus, Short-Hand Operators | CPP Video Tutorial
C++ Video Tutorial | CPP IF ELSE | Conditional Statement
C++ Nested IF ELSE and IF ELSEIF | CPP Programming Video Tutorial
C++ Logical and Comparison Operators | CPP Video Tutorial
C++ Ternary Operator (Conditional Operator) | CPP Video Tutorial
C++ Video Tutorial | While Loop | Introduction to Looping in CPP
CPP Do While Loop with Example | C++ Video Tutorial
CPP For Loop with Example | C++ Video Tutorials
Introduction to ARRAYS in CPP | C++ Video Tutorial
Two Dimensional ( 2D ) and Multidimensional Arrays in CPP | C++ Video Tutorial
Introduction to CPP Functions | Subroutines | C++ Video Tutorial
CPP Function Parameters | Returning Values from Functions | C++ Video Tutorial
C++ Default Function Parameters | CPP Video Tutorial
C++ Inline Function | Inline Keyword | CPP Video Tutorial
C++ Local Global Variable Scopes | CPP Video Tutorial
C++ Break Statement with Example | CPP Programming Video Tutorial
C++ Continue Statement with Example | CPP Programming Video Tutorial
C++ Switch Statement with Example | CPP Programming Video Tutorial
Using Range in the Case Values of Switch Statement | C++ Programming Video Tutorial
C++ Multiple Return Statements in Functions | CPP Programming Video Tutorial
Address operator in C++ | & Operator | CPP Programming Video Tutorial
Introduction to C++ Pointers | CPP Programming Video Tutorial
Passing an Array to a Function in C++ | CPP Programming Video Tutorial
Pass by Address in C++ with Example | CPP Programming Video Tutorial
Relationship between Arrays and Pointers in C++ with Example | CPP Programming Video Tutorial
Const Keyword with Functions and Arrays in C++ with Example | CPP Programming Video Tutorial
Array Ranges in Functions with Example in C++ | CPP Programming Video Tutorial
Introduction to Structures in C++ | CPP Programming Video Tutorial
Arrow Operator with Pointers to Access Structure Members | CPP Programming Video Tutorial
Passing Structure to Functions by Value, Pointer (Address) | C++ Video Tutorial
Nested Structures and C++ Dot Operator | CPP Programming Video Tutorial
Accessing C++ Nested Structure Members using Arrow Operator | CPP Programming Video Tutorial
C++ Sizeof Operator with Variables, Data types, Structures, Unions | CPP Video Tutorial
Introduction to Unions in C++ | CPP Programming Video Tutorial
New and Delete Operators in C++ | Dynamic Memory Allocation | CPP Programming Video Tutorial
Dynamically Allocating Arrays Depending on User Input in C++ | CPP Programming Video Tutorial
Avoiding Dangling Pointer Reference in C++ | CPP Programming Video Tutorial
Automatic Type Deduction C++11 Feature | CPP Programming Video Tutorial
For Each Loop | Range Based For Loop | CPP Programming Video Tutorial
Introduction to Strings in C++ | CPP Programming Video Tutorial
Recursive Function and Recursion in C++ | CPP Programming Video Tutorial
Function Overloading in C++ | CPP Programming Video Tutorial
C++ Object Oriented Programming Video Tutorial | Introducing Classes, Objects
C++ OOPS Video Tutorials for Beginners | Class Properties, Methods, Members
Creating Objects from a Class in Different Ways | C++ Object Oriented Programming Tutorial
Scope Resolution Operator | Defining Methods outside Class definition in C++ | Video Tutorial
Private Access Specifier | C++ Object Oriented Programming Video Tutorial
Class Constructors | C++ Object Oriented Programming Video Tutorial
Overloading Class Constructors | C++ Object Oriented Programming Video Tutorial
Default Class Constructor Parameters | C++ OOPS Video Tutorial
Destructors in a Class | C++ Object Oriented Tutorial
C++ Destructors to Release Resources with example | CPP Object Oriented Programming Tutorial
C++ Static Variables and Members in Class | CPP Object Oriented Programming Video Tutorial
C++ Static Methods in Classes | CPP Object Oriented Video Tutorial
Friend Function | CPP Object Oriented Programming Video Tutorial
Inheritance, Poly Morphism | Introduction | CPP OOPS Video Tutorial
C++ Protected Access Modifier in Classes | CPP Object Oriented Video Tutorial
C++ Access Control and Inheritance | Object Oriented Programming Video Tutorial
Public Inheritance in C++ | Object Oriented Programming Video Tutorial
Protected Inheritance in C++ | Object Oriented Programming Video Tutorial
Private Inheritance in C++ | Cpp Video Tutorial
Changing Access Level of Base Class Members in Derived Class in C++
Order of Execution of Constructors and Destructors in Inheritance in C++
C++ Multiple Inheritance Explained | Cpp Video Tutorial
C++ Calling and Passing Values to Base Class Constructor in Derived Class
C++ Overriding Base Class Methods in Derived Class | Cpp Video Tutorial
Accessing the Overridden Methods in C++ | Cpp Video Tutorial
C++ this Keyword | Cpp Video Tutorial
C++ Calling Methods Using Base Class Type | Cpp Video Tutorial
Polymorphism in C++ and Virtual Functions / Methods | CPP Video Tutorial
C++ Virtual Function | Inherited Attributes, Hierarchical Nature | Cpp Video Tutorial
C++ Pure Virtual Functions, Abstract Classes | Cpp Video Tutorial
C++ Diamond problem in OOPS, Solution using Virtual Inheritance with Example
Nested Classes or Inner classes in C++ | CPP Video Tutorial
Local Classes in C++ | Cpp Video Tutorial
C++ Operator Overloading Introduction | Plus + Operator | Video Tutorial
C++ Overloading "-" Operator | Define Operator Function outside Class | Video Tutorial
Overloading Short Hand Operators | Operator Function as Friend Function | C++ Video Tutorial
Overloading Increment and Decrement Operators in Prefix form | C++ Video Tutorial
Overloading Increment and Decrement Operators in Postfix form | C++ Video Tutorial
Overloading Special [ ] C++ Array Subscript Operator | Cpp Video Tutorial
Overloading C++ Function Call Operator ( ) | Cpp Video Tutorial
Overloading Arrow Operator | Class Member Access Operator | C++ Tutorial
Rules and Restrictions for Operator Overloading in C++
Introduction to Exception Handling | try, catch and throw | C++ Tutorial
Available C++ Standard Exception Classes / Types and using them
Multiple Catch Blocks | Catching All Exceptions in C++
Functions Throwing Exceptions | C++ Video Tutorial
C++ Nested Try Catch statements | Re throwing Exceptions
Creating Custom, User Defined Exception Class | C++ Video Tutorial
Overloading New and Delete Operators | C++ Programming Video Tutorial
Overloading C++ Stream Insertion, Extraction Operators | C++ Programming Tutorial
CPP Copy Constructor with Example | C++ Programming Video Tutorial
C++ IO Stream | Introduction
Set and Unset Format Flags of IO streams | C++ Tutorial
Reading and Displaying Boolean Values as TRUE and FALSE instead of 0 and 1
Precision Fill Width parameters with C++ IO Streams | video Tutorial
C++ iomanip class | using Manipulators with IO Streams | CPP Programming Video Tutorial
Writing your own Manipulator function on C++ IO Streams | Video Tutorial
String Class in C++ | Methods and More | CPP Programming Video Tutorial
C++ getline Function | Reading an Entire Line from Streams | Video Tutorial
C++ File Handling | Creating and Opening | fstream, ifstream, ofstream | Video Tutorial
Writing to a File in C++ using Ofstream Class | Video Tutorial
Reading from a File using ifstream class | C++ Video Tutorial
fstream Class | Appending to a File in C++ | CPP Programming Video Tutorial
C++ File Position Indicators | Get, Put | tellg tellp | seekg seekp
Binary Files in C++ | CPP Programming File Handling Video Tutorial
C++ Binary Files | Read, Write Methods | CPP Programming File Management Video Tutorial
Stringstream in C++ | CPP Programming Video Tutorial
#Define PreProcessor Directive | C++ Video Tutorial
#include PreProcessor Directives in C++ Programming Video Tutorial
Function like Macros | C++ PreProcessor Video Tutorial
if endif elif else Conditional Compilation Macros | C++ Video Tutorial
Conditional Compilation Macros | ifdef ifndef | C++ Video Tutorial
#undef Pre Processor Directive | C++ Video Tutorial
C++ Predefined macros | LINE PreProcessor Directive | CPP Video Tutorial
Generic Programming in C++ and Templates | CPP Video Tutorial
Multiple Parameters and Return Values | C++ Generic Programming Video Tutorial
Passing Standard Parameters to C++ Generic Functions | CPP Video Tutorial
Generic Functions with Multiple Generic Types | C++ Programming Video Tutorial
Explicitly Overloading Generic Functions | C++ Video Tutorial
Overloading Generic Function Template | C++ Programming Video Tutorial
Introduction to C++ Generic Classes | CPP Generic Programming Video Tutorial
C++ Generic Class with more than one Generic Type | CPP Programming Video Tutorials
Default Data Types as Parameters to Generic Classes | C++ Programming Video Tutorial
Explicit Specialisation of Generic Class | C++ Generic Programming Video Tutorial
Introduction to C++ Namespace | CPP Programming Video Tutorial
C++ Nested Namespace | CPP Programming Video Tutorial
UnNamed or Anonymous Namespaces in C++ | CPP Programming Video Tutorials
Nested UnNamed or Anonymous Namespaces | C++ Programming Video Tutorials
C++ Namespace Aliases | Giving a New Name to an Existing Namespace | Video Tutorial
Inline Nested Namespace in C++ | CPP Programming Video Tutorial
Writing Classes in Separate Files using #define in C++ | CPP Video Tutorial
C++ Even or Odd Number Program | CPP video Tutorial
CPP Introduction, History, Features | C++ Programming Video Tutorials for Beginners
How C++ Works, Compilers, Linkers, IDEss | CPP Programming Language Tutorial
Libraries In C/C++ For Machine Learning
TensorFlow
Caffe
Microsoft Cognitive Toolkit (CNTK)
mlpack Library
DyNet
Shogun
FANN
OpenNN
SHARK Library
Armadillo