IT. Expert System.

Global variable is defined at the top of the program file and it can be visible and modified by any function that may reference it. Global variables are initalised automatically by the system when you define them! Data Type Initialser int 0 char '\0' float 0 pointer NULL If same variable name is being used for global and local variable then local variable takes preference in its scope. But it is not a good practice to use global variables and local variables with the same name.

Syntax:

int a; /*global variable*/
main(){

/*code goes here*/

}

Example:

int i=4;          /* Global definition   */
   
   main()
   {
       i++;          /* Global variable     */
       func();
       printf( "Value of i = %d -- main function\n", i );
   }

   func()
   {
       int i=10;     /* Local definition */
       i++;          /* Local variable    */
       printf( "Value of i = %d -- func() function\n", i );
   }

   This will produce following result
   Value of i = 11 -- func() function
   Value of i = 5 -- main function

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