Rules for constructing C constant

1. Integer Constants in C:

• An integer constant must have at least one digit.
• It must not have a decimal point.
• It can either be positive or negative.
• No commas or blanks are allowed within an integer constant.
• If no sign precedes an integer constant, it is assumed to be positive.
• The allowable range for integer constants is -32768 to 32767.

2. Real constants in C:

• A real constant must have at least one digit
• It must have a decimal point
• It could be either positive or negative
• If no sign precedes an integer constant, it is assumed to be positive.
• No commas or blanks are allowed within a real constant.

3. Character and string constants in C:

• A character constant is a single alphabet, a single digit or a single special symbol enclosed within single quotes.
• The maximum length of a character constant is 1 character.
• String constants are  enclosed within double quotes.