Technotes

Technote TE 09

February 1990

You Said It Would Be A Long Time

_LongSecs2Date, the routine that translates a LongDateTime to a LongDateRec, has a bug caused by using a variable that has not been properly initialized. This bug rears its ugly head when negative values are passed to the routine. System Software 6.0.4 and later fix this bug, and there is a simple solution for earlier systems.

If using System Software 6.0.3 and earlier, if you call _LongSecs2Date once before you really want to use it, the variable is cleared. After the initial call, _LongSecs2Date works correctly.

For example:

MPW Pascal

PROCEDURE DoDateStuff;
VAR
  lsecs: LongDateTime;
  ldr:   LongDateRec;
BEGIN
  InitDateCache(dcr);
  lsecs := 0;
  LongSecs2Date(lsecs,ldr);
  {now you can call LongSecs2Date for real}

END;

void DoDateStuff()
{
  LongDateTime lsecs;
  LongDateRec  ldr;


/* work around the bug */
  lsecs = 0;
  LongSecs2Date(&lsecs,&ldr);
/* now call LongSecs2Date for real */
}

Any String To Date

The routine _String2Date was originally designed to be as forgiving as possible. It is so forgiving that it accepts any non-alphabetic character as a separator and accepts a single number as a valid date. For instance, if you pass _String2Date a string like "<20" it generously assumes that the less than sign (<) is intended as a divider and that "20" must be intended as a day, since there are only 12 months in a year. It returns a result of noErr and a date which is the twentieth of the current month in the current year. The string "<3*3" produces March 3 of the current year, while "4>1" politely gives the date April 1 of the current year.

This forgiveness really is not a bug, but a feature. Unfortunately it isn't a feature that has been greatly appreciated in the developer community. For that reason, the rules for date and time dividers are tighter in System 7.0. Current thinking is that all list separators now used in 'itl0' resources will be allowed with a few common date separators used in the U.S. (e.g., colon (:) and hyphen (-)). For now, it is important to be aware of, shall we say, the flexibility of _String2Date and avoid thinking of it as an intelligent date parser. If you want to parse something, you can use _IntlTokenize.

Further Reference:

• * Inside Macintosh, Volume V, The Script Manager
• * The Script Manager 2.0, Interim Chapter (DTS)