What are Constant and Variable

Definition of constant and variable.
Constant: An entity that does not change.
Variable: An entity that may change.
Let see example of both constant and variable.

In C language, We declare an integer variable like this

   int n;    //declaration of n

Now initialize variable n

 n = 45;   // initialization of n

The value stored in n is 45. Now we can change the value that is stored in n.

 n = 32;

We saw that n can take different value while we can not change value of 45. (its value is 45).

So here n is a variable and 45, 32 are constants.