Difference in time

/* 
   Returns difference in time between a given start hour, 
   start min and end hour and end min 
*/

int difftime(int sh, int sm, int eh, int em)
{
   int s, e ;
   s = 60*(sh-0) + sm ;
   e = 60*(eh-0) + em ;
   e -=s ;

   if (e < 0)
   e += 60 * 24 ;
   return e ;
}