Listing 5

// check for null string
if (retValue=isnullstr_m(&condition, str2)) {
  fprintf(
    stderr, 
    "error %d from isnullstr_m.\n", 
    retValue
  );
}
else {
  if (condition) {
    printf("(NULL)\n");
  }
}
// check for emptry string
if (retValue=isemptystr_m(&condition, str2)) {
  fprintf(
    stderr, 
    "error %d from isemptystr_m.\n", 
    retValue
  );
}
else {
  if (condition) {
    printf("(empty)\n");
  }
}