Constants ( Literals )

Constants ( Literals )

The values cannot be changed during the execution of program are called constants. The fixed values are also called literals.

Types of Constants ( Literals )

  1. Integer Constants
  2. Float Constants
  3. Character Constants
  4. String Constants

Integer Constants

Integer Constants are numbers that do not have a decimal point or an exponential part.
They can be represented as:
Decimal Number 0 to 9 Ex: 7, 8, 6, -80, 786, etc.,
Octal Number 0 to 7 EX: 0, 012, 052, etc.,
Hexadecimal Number  0 to 9, A, B, C, D, E, F  Ex: 0x786, 0xA123, 0x2b, etc., 

Float Constants

Float Constants are numbers that have a decimal point or an exponential part.
They can be represented as:
 Float Constant  Value
7.867e3 7,867
4e-11 0.00000000004
1e+5 100000
7.e10 60000000000
0.16 0.16

Character Constants

Character Constants contains a single character enclosed within a single quotation mark symbol.
Ex: 'M', 'A', '9', '-', etc.., .

String Constants

A String Constants contains a sequence of characters or escape sequences enclosed in double quotation mark symbols.
EX:"MDSN", "Learn C\n", " ", etc.., .

How to Define a Constant in C

There are two simple ways to define Constants.
  1. #define ( Preprocessor)
    Example:
    
#include <stdio.h>
#define Length 10    //Preprocessor
#define Width 5      //Preprocessor
int main(){
int Area;
Area=Length*Width;
printf("Area=%d",Area);
return 0;
}
  2. const ( Keyword )
    Example:
    
 #include <stdio.h>
int main(){
const Length=10, Width=5;  // Keyword
int Area;
Area=Length*Width;
printf("Area=%d",Area);
return 0;
}