What is Constant and how to declare a constant in C++ ?

Constant:

Constant is a permanent value that cannot be changed. In C++ constant can be declared by using const keyword.

Types of constant:

1. Numeric

• int constant
• float constant

2. Character

• string constant
• character constant

const int g =9.8;

If you change the value of constant after initialization an error will be generated by the compiler cannot modify const object.

#define:

#define is also used to define a constant.

General syntax:

#define constant_name value

  Example: #define pai 3.14