C Identifiers


Definition:

Identifiers are sequences of characters used for naming variables, functions, new data types, and preprocessor macros. 

Rules:

  • Identifier can be include letters uppercase(A-Z) and lowercase(a-z)
  • Identifier can be decimal digits(0-9). 
  • The first character of an identifier cannot be a digit. 
  • You Can Include underscore character ?_? in identifiers.The first character of an identifier cannot be a underscore(Some Compilers Accept underscore as a first Charecter). 
  • Lowercase letters and uppercase letters are distinct, such that foo and FOO are two different identifiers. 
  • When using GNU extensions, you can also include the dollar sign character ?$? in identifiers.

Example:

int amount;
char name[20];