C-TUTORIAL

Introduction C

Constants

Variables

Identifiers/ keywords

Data Types

Operators

Library Functions

Input/ output statements

Control statements

Loop Control Structure

Functions

Classes

Preprocessor Directives

Arrays

String

Pointers

Structure/ Union

File Handling

Exercises

## Constant

- Constant is a quantity that does’t change with the execution of the program.
- Constant value remains same throughout the whole program execution.
- Example Int a=5; char b=”INDIA”; etc.
- Constant may be numbers , characters or strings.
- Example : Z=3.2*X+8-Y;
- Here 3.2 and 8 are constants and Z, X, Y are variable.

**Types of Constants:**

- Integer constant
- Real or Floating Point constant
- Character Constant
- String Constant

Integer constant | Real Point constant | Character constant | String constant |

**Integer Constant:**

- Integer constant consists of a sequence of digits.
- Integer constant must have at least one digit.
- Integer constant must not have a decimal point.
- Integer constant may be either positive or negative.
- No commas or blank spaces are allowed in an integer constant .
- Integer constant used 2 byte of memory to be stored .
- Range of integer constant is -32768 to +32767.
- Vaild Integer constant : 0, 53, -343, 9999.

**2. Floating Point Constant:**

- Floating point constant can be written in two forms, Fractional form and exponential form.
- Floating Point constant will occupy 4 bytes of memory.
- Floating point constant must have at least one digit.
- There must be a decimal point in Floating Point constant.
- No commas or blank space are allowed in floating point constant.
- Valid floating point constant
- +34.53, 34.33, -32.11 and 5.0 etc. are valid floating point constant.
- Invalid floating point constant
- 4,23 and 34-33 etc. are invalid floating point constant.

**3. Character Constant:**

- A character constant is a single character enclosed in apostrophes means single quotation marks.
- Character constant may be an alphabet, digit or special symbol.
- Range of Character Constant is -128 to 127.
- Example: ‘A’ , ‘4’ , ‘-’ , ‘d’ and ‘=’.

**4. String Constant :**

- String Constant is a constant that consists of any number of consecutive characters.
- A sequence of characters enclosed by double question marks .
- Example: “Jhon” , “INDIA”, “DEVIL” , “ ” and “3422” etc. are example of string constant.