C++ Basic Syntax

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:

#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.