Fundamentals of C Programming

Identifier :

An identifier is a name having a few letters , numbers and special type of character. It is used to identify a variable,function,symbolic constant. Am identifier can be written with a maximum of 31 characters.
Example:
identifier

Tokens:

C program has punctuation marks, keywords and operators as the smallest individual units are referred to as Tokens.

c tokens

Keywords in C:

c keywords

Note: All the keywords must be written in lower case.

Constants :

Any unchanged value in a program during the program execution is called constant.
There mainly two types of Constants in C language.
1. Numeric Constants
2. String or Character Constant
Numeric Constants :
There are two types of numeric constants.
(i) Integer Constant
(ii) Real or floating-point constant

(i) Integer Constant : An integer constant is a signed or unsigned whole number.
Example: -25, +25

(ii) Real or floating-point constant : Any signed or unsigned number with fractional part is called real or floating-point constant. A real constant can be written in decimal or exponential form.
Example:

  • Decimal form
    0.542
    +355.0
    -3.14

  • exponential form
    exponent