spyglass: $cat compare.c 
 /*
  *  compare two numbers without relational operators
  */


int cmp(int a,int b)
{

  int g=0 ;
  ((    ( !((b+1)/b)  && (!( a/b) ) ) 
     || ( ((a+1)/a)  && (a/b) ) 
   ) && (g=a))
   || (g=b) ;
  return g;
}



int main()
{
  int a,b;
  int g;

  printf("Enter two numbers(0 0 to exit):");
  scanf("%d %d", &a , &b );
  while( a && b ){

     g = cmp(a,b);
     printf("greatest = %d ,small =%d \n", g, a+b-g );

     printf("Enter two numbers:");
     scanf("%d %d", &a , &b );
  }

}
spyglass: $gcc compare.c

spyglass: $./a.out 
Enter two numbers(0 0 to exit):10 2   
greatest = 10 ,small =2 
Enter two numbers:2 10
greatest = 10 ,small =2 
Enter two numbers:-2 10
greatest = 10 ,small =-2 
Enter two numbers:10 -2  
greatest = 10 ,small =-2 
Enter two numbers:-2 -10   
greatest = -2 ,small =-10 
Enter two numbers:-10 -2
greatest = -2 ,small =-10 
Enter two numbers:-10 2
greatest = 2 ,small =-10 
Enter two numbers:2 -10
greatest = 2 ,small =-10 
Enter two numbers:0 0
spyglass: $