Fundamentals of C Programming

Identifier:

An identifier is a name having a few letters, numbers and a special type of character. It is used to identify a variable, function, or symbolic constant. An 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 lowercase.

Constants :

Any unchanged value in a program during the program execution is called constant. There are 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: 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 a fractional part is called real or floating-point constant. A real constant can be written in decimal or exponential form.

Example: