What is Constant in C Language?
Constant in C refers to a value which cannot be changed i.e. a fixed value, like – 5, 5.6, “C Language”, 'C' etc.
What are the types of C constant?
Primarily there are 3 types of C constant:
- Integer Constant
- Real Constant
- Character Constant
What are the rules of constructing Integer constant?
The rules of constructing Integer constant are as follows:
- An integer constant must have at least one digit.
- It must not have a decimal point.
Ex: 3.5 is wrong
- It can be either positive or negative.
Ex: +45 or -45
- If no sign precedes an integer constant it is assumed to be positive.
Ex: 67 is by default positive
- No commas or blanks are allowed within an integer constant.
Ex: 6,7 and 6 7 are wrong
- The allowable range for integer constants is -32768 to 32767 in case of a 16 bit compiler
Ex: 3563467 or -6575855 is out of range of integer in case of 16 bit compiler
What are the rules of constructing real or floating point constant?
- A real constant must have at least one digit.
- It must have a decimal point.
- It could be either positive or negative.
Ex: +34.54 or -35.76
- Default sign is positive.
Ex: 453.76 s by default positive
- No commas or blanks are allowed within a real constant.
Ex: 6.,7 and 6. 7 are wrong
- The real constant can also be written as exponential form like 65.45e6, where the part before 'e' is known as mantissa and the part after e is called exponent.
- 7. The mantissa part must have decimal point whereas the exponent part must be an integer
- Both the mantissa part, and the exponent part may have a positive or negative sign, default is positive.
- Range of real constants expressed in exponential form is -3.4e38 to 3.4e38.
What are the rules of constructing Character constant?
- Any single alphabet or single digit or single special symbol enclosed within the single inverted comma is treated as character constant.
Ex: 'b' or 'B' or '5' or '-' etc
but '45' or 'fs' or '=-' are wrong because they enclose more than a single character.