Variables

    A variable  is a named location in memory that is used to hold a value. Variables can hold one value at a time. The value of variable can be changed during execution of program . It is different from constant . Constant is a value that can not be changed during execution of program.

Rules for variable names :

•   A variable is combination of alphabets, digit and underscore.
• First character should be alphabet.
• No special symbol other than underscore.
• We can not use keywords as variable names.
• Variable names are case sensitive.
• there is no blank space or a comma in  a variable.

Examples : D_o_B          total       area1        Area

Declaration of Variable :

The declaration of variable includes-

• Type of variable
• Variable name

Examples : int  x;

                    int  x,y,z,total;

                    float  sal ;

                    char grade ;

                    int int_type;

Initialization of variable :

 When a variable is declared it contains undefined value, called garbage value. We can assign some initial value to the variable at the time of declaration. Assigning a value to the variable at the time of declaration is called initialization of variable.              

                    int  x = 5;

                    float  y =3.7;

                    char ch = ' N' ;

                    int a, b, c = 10;