#include<stdio.h>
#include<stdlib.h>      //include stdlib for malloc()

//make nothing global

void fun(int**,int**);     /*pass double pointers so that changes made to them are visible outside fun()*/

int main(void)
{
    int s;
    int *p1,*p2;
    fun(&p1,&p2);       //Address of p1 & p2 must be passed as they are single pointers
    s=*p1 + *p2;

    printf("Sum= %d",s);
    return 0;
}

void fun(int **dp1,int **dp2)
{
    *dp1=malloc(sizeof(int));     //allocate memory to use it outside fun()
    *dp2=malloc(sizeof(int));
    **dp1=3;
    **dp2=5;
}