Programming in C

While defining a constant there are some rules that must be followed.

for example: To define integer constant rules are:

-It must have at least one digit.

-There must be no decimal point.

-It does not allow any blanks or commas.

-An integer constant can be both negative and positive.

-We assume an integer constant to be positive if there is no sign in front of that constant.

-The allowable range for this type of constant is from -32768 to 32767.

similarly, rules exist for the string constant, real constant, character constant, floating-point constant, etc.

• And those constants which do not follow these rules are considered as invalid constants.

Ex:

‘ab’ is an invalid character constant (since char must have only one literal)

25,234 is an invalid integer constant (since is not an integer)

25 is an invalid floating-point constant (since it doesn’t contain . a period), etc.