write a c program demonstrate to call by reference

Program:

#include<stdio.h>
#include<conio.h>
void add(int *a);
void main()
{
int x;
printf("enter any number");
scanf("%d",&x);
add(&x);
printf("\n after calling function variable value is %d",x);
getch();
}
void add(int *a)
{
*a=*a+10;
printf("\n in Called function variable value is %d",*a);
}

Output:

enter any number 10

 in Called function variable value is 20
 after calling function variable value is 20