mismatch (const char *a, const char *b)
{
  if (a == b)
    return 0;
  if ((a == NULL) || (b == NULL))
    return 1;
  return 0 != strcmp (a, b);
}
mismatch (const char *a, const char *b)
{
  if (a == b)
    return 0;
  if ((a == NULL) || (b == NULL))
    return 1;
  return 0 != strcmp (a, b);
}