Call by reference in C language

 Call by Reference :

Definition: It is a calling function by address of variable.

Example for Call by reference: 

#include<iostream>

int main()

{

int a=10,b=20;

void display(int *, int *);

display(&a, &b);

return 0;

}

 

 void display(int *x, int *y)

 {

    printf("\n %d  %d ",*x, *y);

}

 

Swapping two variables using call by reference function:

#include<iostream>

int main()

{

int a=10,b=20;

void swap(int *, int * );

            printf("\b Before swap ");

            printf("\n %d %d",a,b);

            swap(&a,&b);

            printf("\n After swap");

            printf("\n %d %d",a,b);

return 0;

 }

 

 void swap(int *x, int *y)

 {

   int temp;

            temp=*x;

            *x=*y;

            *y=temp;

 }

 

O/p:

            Before swap

10        20

After  swap

20        10

 

Reason:

            In the above example, swap() function is call by reference, its arguments are pointers, which receives address of variables. These arguments works with actual copies ( passing variable).

Hence Swapping operation takes place on original copies through address ( pointers )

 

In call  by reference  function, the changes made on arguments will be reflected on actual variables ( passing variable);