Variable Declaration and Datatype in C language with their uses

Variable Declaration

The memory area used for storing the input data or intermediate data , is called variable.

There are some rules to declare the variables in C language:

1. Must be start with alphabet.

2. Special character is not allowed except _(Underscore).

3. Variable may be alphanumeric.

4. Variable name must be different from keywords used in C language like printf, scanf,eof etc.

The syntax for variable declaration is 

1. <datatype><space> <variablename>

2. <datatype><space> <variablename>=<value>

for example: int x;

int Num=10;

char str;

char str[45];

Datatype used in C language

A datatype is used to instruct the compiler that what type of data will be stored in variable. Different type of datatype are used in C language is:

1. int(2 to 4 byte)

2. float(4 Byte)

3. cha(1 byte)

4. double(8 byte)

5. long(4 Byte)

int and long datatype is used to store the integer , float and double are used to store the real values and char is used to store the character values.

Example:

int a,b;

char ch;

float Num;