Reverse number using pointer initialization to normal

#include < stdio.h >
#include < conio.h > 
#include < alloc.h >
void main()
{
    long *np,*revp,n,rev,*np1,n1;
    clrscr();
    np=&n;
    revp=&rev;
    np1=&n1;
    printf("\nEnter n:");
    scanf("%ld",np);
    *revp=0;
    *np1=*np;
    while(*np!=0)
    {
        *revp=*revp*10+(*np%10);
        *np=*np/10;
    }
    printf("\nReverse of %ld is %ld",*np1,*revp);
} // main