C Constants



What is Constant ?

Constant in C means the content whose value does not change at the time of execution of a program.

Definition :

[box]Constant means “Whose value cannot be changed“[/box]

Explanation :

  • Initially 5 is Stored in memory location and name x is given to it
  • After We are assigning the new value (3) to the same memory location
  • This would Overwrite the earlier value 5 since memory location can hold only one value at a time
  • The value of ‘3’,’5′ do not change ,so they are constants
  • In Short the ‘Values of Constant Does not Change‘.

Different Types of C Constants :

Constant Type of Value Stored
Integer Constant Constant which stores integer value
Floating Constant Constant which stores float value
Character Constant Constant which stores character value
String Constant Constant which stores string value

How to Declare Constant in C :

We can declare constant using const variable. Suppose we need to declare constant of type integer then we can have following two ways to declare it –

const int a = 1; 
int const a = 1;

above declaration is bit confusing but no need to worry, We can start reading these variables from right to left. i.e

Declaration Explanation
const int a = 1;
read as “a is an integer which is constant”
int const a = 1;
read as “a is a constant integer”