c++

When we consider a C++ program, it can be defined as a collection of objects that communicate via invoking each other's methods. Let us now briefly look into what do class, object, methods and instant variables mean.
Object - Objects have states and behaviors.
Example: A dog has states - color, name, breed as well as behaviors - wagging, barking, eating. An object is an instance of a class.
Class - A class can be defined as a template/blueprint that describes the behaviors/states that object of its type support.
Methods - A method is basically a behavior. A class can contain many methods. It is in methods where the logics are written, data is manipulated and all the actions are executed.
Instant Variables - Each object has its unique set of instant variables. An object's state is created by the values assigned to these instant variables.
C++ Program Structure:
Let us look at a simple code that would print the words Hello World.

#include <iostream> 

using namespace std;

// main() is where program execution begins.

int main()

 {   cout << "Hello World";

 // prints Hello World 

  return 0;

 }

Let us look various parts of the above program:

The C++ language defines several headers, which contain information that is either necessary or useful to your program. For this program, the header <iostream> is needed.

The line using namespace std; tells the compiler to use the std namespace. Namespaces are a relatively recent addition to C++.

The next line // main() is where program execution begins. is a single-line comment available in C++. Single-line comments begin with // and stop at the end of the line.

The line int main() is the main function where program execution begins.

The next line cout << "This is my first C++ program."; causes the message "This is my first C++ program" to be displayed on the screen.

The next line return 0; terminates main( )function and causes it to return the value 0 to the calling process.