A variable is a name of memory location. It is used to store data. Its value can be changed and it can be reused many times.

  • Syntax to declare a variable in C

    data_type  variable_name = value ;

    Example)
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    #include <stdio.h>
    #include <conio.h>
    int main()
    {
        int a=56;//declaring and initializing the variable
        int b=65;//declaring and initializing the variable
        printf("value of a is %d",a);
        printf("\n");
        printf("value of b is %d",b);
        return 0;
    }
    
    Output:
    value of a is 56
    value of b is 65

    If no input values are assigned by the user than system will gives a default value called garbage value.

  • Rules for defining variables

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

    • A variable can have alphabets, digits and underscore.

    • A variable name can start with alphabet and underscore only. It can't start with digit.

    • No white space is allowed within variable name.

    • A variable name must not be any reserved word or keyword e.g. int, float,double,byte etc.

  • Garbage value

    Garbage value can be any value given by system and that is no way related to correct programs. This is a disadvantage of C programming language and in C programming it can overcome using variable initialization.

    Example)
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    #include <stdio.h>
    int main()
    {
        int a;//declaring 
        int b;//declaring 
        printf("value of a is %d",a);//printing Garbage  value 
        printf("\n");
        printf("value of b is %d",b);
        return 0;
    }
    
Example on this is page is tested on Code Block .

What next?

The next topic is Types of Variables in C

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