• Friday, 11 March 2016

    Variable is an identifier which holds data or another one variable. It is an identifier whose value can be changed at the execution time of program. It is used to identify input data in a program.



    Syntax

    Variable_name = value;


    Rules to declare a Variable

    To Declare any variable in C language you need to follow rules and regulation of C Language, which is given below;

    • Every variable name should start with alphabets or underscore (_).
    • No spaces are allowed in variable declaration.
    • Except underscore (_) no other special symbol are allowed in the middle of the variable declaration (not allowed -> roll-no, allowed -> roll_no).
    • Maximum length of variable is 8 characters depend on compiler and operation system.
    • Every variable name always should exist in the left hand side of assignment operator (invalid -> 10=a; valid -> a=10;).
    • No keyword should access variable name (int for <- invalid because for is keyword).
    Note: In a c program variable name always can be used to identify the input or output data.

    Variable declarations

    This is the process of allocating sufficient memory space for the data in term of variable.

    Syntax

    Datatype variable_name; int a;
    variable declaration
    If no input values are assigned by the user than system will gives a default value called garbage value.

    Variable initialization

    It is the process of allocating sufficient memory space with user defined values.

    Syntax

    Datatype nariable_name=value;
    

    Example

    int  b = 30;
    
    variable initilization

    Variable assignment

    It is a process of assigning a value to a variable.

    Syntax

    Variable_Name = value

    Example

    int  a= 20;
    int b;
    variable Assignement

    Example

    b = 25; // --> direct assigned variable
    b = a;  // --> assigned value in term of variable
    b = a+15;  // --> assigned value as term of expression
    
    variable Assignement
    variable is changable,. when you can change value , thai is variable... 


              


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