Function            isallalphanum - are all characters in string
                                        alphanumeric

  Syntax              boolean isallalphanum(char *str);

  Prototype in        stringhk.h

  Remarks             checks if all characters in str are alphanumeric.

  Return value        returns TRUE if all characters in str are
                      alphanumeric, FALSE otherwise.

  See also            isallalpha(), isalllower(), isallupper()