/*
** strcmp -- return -1, 0, +1 depending on str1 <, =, > str2
*/
strcmp(str1, str2)  char *str1, *str2;  {
  char c1, c2;
  while((c1 = *str1++) == (c2 = *str2++)) if(c1==NULL) return 0;
  return sign(c1-c2);
  }