# 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:**

## Tokens:

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

__Keywords in C:__

**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**