C Programming Variable Declarations and Definitions

Variable:

Variable is an identifier whose value can be changed. or which store the data
Example:
int x=10;
x=20;

Variable declaration rules:

1. Variable name must be starts with alphabet or underscore or dollar symbol.
Example:
int age=10;
int _age=20;
int $age=30;

2. The max length of the Variable name is upto 32 characters.

3. If Variable name contains more than one word ,the second word onwards first letter should be uppercase letter.
Example:
int studentAge=10;
int studentAgeDetails=10;

4. No spaces are allowed at the middle of the Variable declaration.
Example:
int student Age=10; (Invalid);

5. If Variable value contains constant value that Variable name must be uppercase letter.
Example:
const float PI=3.14;

6. If constant Variable name contains more than one word ,it should be separated with underscore.
Example:
const float PI_VALUE=3.14;

7. All keywords are lower case letters.(32 Keywords in C)
Example:
int
float
char

8. We should not take keyword as a Variable name.
Example:
int if=10;(Invalid)
int If=10;(Valid)

Variable Defination types:

1.Initialization
2.Declaration
3.Assignment

Initialization:

It Means initialize the some value to the Variable.
Example:
int x=10;
Here 10 is initialize to the x.

Declaration:

In the declaration no value initialize to the Variable. Example:
int x;

Assignment:

In the assignment assign the value to the Variable or assign Variable to the Variable.
Example:
int x;
x=10;(It is a value to Variable).

int y;
y=x;(It is a Variable to Variable).

C Programming Variable Declarations and Definitions