C Fundamentals:Character Set & Identifiers

 A character is a symbol,digit or alphabet that represent information.These followings valid letters, digits and special characters are allowed in C.

•A-Z(uppercase)

•a-z(lowercase)

•0-9(digits)

•Certain special characters :

     + - * / = % & # ! ? ^ “ ‘ ~ @ $

     \ | < > ( ) [ ] { } : ; . , _ (blank space)

Identifiers: Identifiers are names given to various program elements,such as variables functions and arrays. 


Rules for Identifiers:It consists of letters and digits in any order except that the first character must be a letter.Both uppercase and lowercase letters are permitted.The underscore is also permitted and may be used as the first character of the identifier.Use of others are illegal.

Some valid identifiers:

x                      y12                       sum_1          _temperature

names              area                      tax_rate               TABLE

Some invalid identifiers:

4th           “x”          order-no         error flag