Keywords and Identifiers in C Programming

Keywords

C has a set of reserved keywords. They have a basic meaning behind them. They are written in lower case. In all there are 32 keywords.

Following table provides with all the keywords:

autobreakcasechar
constcontinuedefaultdouble
elseenumexternfloat
forgotointlong
registerreturnshortsigned
sizeofstructswitchtypedef
unionunsignedvoidvolatile
doifstaticwhile

Identifiers


Identifiers are the names given to the variables, constants, functions and the user-defined data.
Identifiers are written by keeping in mind a set of rules.

The rules are as follows:

1. Special characters or punctuation marks like #, $, ^,?, . etc cannot be included. But an '_' underscore can be used.
2. Two successive underscores cannot be used at the same time.
3. Any keywords cannot be used as an identifier.
4. Identifiers are case-sensitive.
5. The identifier name can begin with an alphabet or an underscore.
6. An identifier can be of any reasonable length, but it should not contain more than 31 characters.