#include<stdio.h>

int *p1,*p2;      //make pointers global
int a,b;          //make variables to be referenced global

void fun(void);     //No need to pass any arguments, as p1,p2 are global

int main(void)
{
    int s;
    fun();
    s=*p1 + *p2;

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

void fun(void)
{
    a=3;
    b=5;
    p1=&a;
    p2=&b;
}