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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