Function            iszip - is a zip code valid for a state

  Syntax              boolean iszip(char *state, char *zip);

  Prototype in        statehk.h

  Remarks             iszip() checks if a zip code is valid for the state
                      given by its abbreviation. See isstate for valid
                      state abbreviations.

                      Currently, iszip() requires the zip code to be a
                      string, which is internally converted to a long via
                      atol(). This was done to provide potential future
                      expansion to support non-numeric zip codes (i.e.
                      Canada, etc.) in the future.

  Return value        returns TRUE if the zip code is valid for the state
                      given. If the state abbreviation is not valid, or
                      the zip code is not valid for the state, FALSE is
                      returned.

  Note                For Canal Zone (CZ), any zip code will return as
                      valid. I could not determine the range of valid zip
                      codes for the Canal Zone.

  See also            statehk.h
                      isstate(), stateindex()

  Example             #include <statehk.h>

                      {
                           printf("11554 is ");
                           if (!iszip("NY","11554"))
                                printf("NOT ");
                           printf("a valid zip code for NY\n");
                      }

  Program output      AL is a valid state abbreviation