Constant

Constant

1. Constant is an entity that does not change during program execution. Example when we write number=10 than 10 is constant in all program and never change value.


2. There are mainly two types constants:
   1. Primary constants
      • Integer constant
      
      
      • Real Constant
      
      
      • character Constant
      
      
   
   
   2. Secondary Constants
      • Array
      
      
      • Structure
      
      
      • Pointer
      
      
      • Union
      
      
   
   

Rules for construction Integer Constant

• At least one digit must have an integer constant


• It can be positive or negative. The general range of integer constant is -32768 to +32767.(NOTE : Normally range depend on compiler.)


• No commas or blank spaces are allowed within integer constant.


• Integer constant must not having decimal point.


• Example of integer constant are as 364,-66,+786,-1

Rules for constructing Floating point or Real constant

• At least one digit must have an real constant.


• Real constant must have decimal point.


• It may be positive or negative.


• No commas or blank spaces are allowed within real constant.


• Example of real point constant : +23.0, 786.786, -0.786, 0.0

 Rules for constructing Character constant

• Any single entity(like as single alphabet, single digit or single symbol) are enclosed within single inverted commas, are called character constant.


• Example of Character constant : 'a', 'A', '*', '4' etc..