C Constants Types

Primary Constant :

  • Integer
  • Float
  • Character

Secondary Constant :

  • Array
  • Pointer
  • Structure
  • Union
  • Enum
Rules of Constructing Integer and Float Constant

Sr.No Rule Integer  Float
1

 Decimal Point

 Not Allowed

 Allowed
2

 Sign

 Positive or Negative

 Positive or Negative
3

 Default Sign

 Positive

 Positive
4

 No of Digits

 At least 1

 At least 1
5

 Min Value

 -32768

 -3.4e38
6 Max Value

 +32767

 3.4e38

Format of Real Number Constant :
Syntax :                                 mantissa e exponent                   

Part
 Type
 Sign
Mantissa Integer Part of Real Number Has Optional +/- Sign
Exponent Power of 10 Has Optional +/- Sign


Note :

  1. Exponent Part Should be Always Integer.
  2. Default Sign is Positive for both Mantissa as well as Exponent
  3. Special Characters not allowed
  4. Spaces are not allowed

Illustrative Examples :

Real Number Representation
4567.45 4.56745e3
0.00045 4.5e-4

 

Consider Example 2 :
  1. Mantissa Should be in between 1 to 9
  2. Number : 0.00045 so shift decimal Point to Right by 4 Digit to obtain Mantissa as 4.5 
  3. Decimal Point is Shifted 4 times to Right 
  4. According to above Fig . Real Number : 4.5 e -4