Comments are text that are ignored by the C++ compiler. Like other languages comments are used for reference for future.

There are two types of comments used in C++. First type is a single line comment that is enclosed within two forward slashes("//") in the begining as well as in the end. The other type is multiline comment that is enclosed between a "/*" and "*/".

#include <iostream.h>
int main()
  {
    int a;
    cout << "Enter a integer::"; //This is a single line comment//
    cin >> a; 
    /* Enter 
       a value for a */
    cout << "Value is::" << a << endl;
    return 0;
  }

    Enter a integer::4
    Value is::4

In the above example both types of comments are used, but the compiler simply compiles the code alone.