A constant is a variable whose value cannot be changed after its definition. Constants in C are the fixed values and its value remains unchanged during the entire execution of the program. Generally, we use const keyword to create a constant.

const double PI = 3.14;

There are two Ways in C to define constants

1. Using const keyword.
2. Using #define preprocessor.

• Constants are also called literals.
• Constants can be any of the data types.
• We can also define a constant using the #define preprocessor directive.