Situation:
The function strftime does return false for negative unix-timestamps.

Problem:
The functions mktime and strtotime return negative values for dates
before 1970-01-01 00:00 UT.
Many users try something like:

strftime($format,strtotime($date_before_1970))

and wonder why this does not work.

If the behavior for timestamps before second 0 
(start of Jan 1., 1970 UT) is undefined why do all other time functions
return negative values ?
The documentation for strftime does not say anything about negative
values for timestamps, too.

Solution:
Let strftime return values (Gregorian calendar) for negative
timestamps.
(Perhaps there should be a warning ?)

Please do not use "all" for the OS field unless you know for certain that it affects all platforms equally.

Most of the datetime related functions (strftime included) are dependent on what support exists in the libraries on the running system.  An example of this variable behavior is the time() function which returns values from -2147483648 to 2147483647 on most unix platforms, but only returns positive values under windows.

On your platform, strftime() only accepts positive values.  That is not to say that strftime only accepts positive values on all platforms.  Have you tried date()?

The strftime manual page already has a warning stating that not all format specifiers are supported on all platforms, perhaps that should be extended to warn of inconsistent support for timestamp values.

I'm having this problem on Redhat 7.3/PHP4.3.2

On our forum software (vBulletin) members profiles are showing "Dec-31-1969" for people born before 1970.

This bug has been fixed in CVS.

In case this was a PHP problem, snapshots of the sources are packaged
every three hours; this change will be in the next snapshot. You can
grab the snapshot at http://snaps.php.net/.
 
In case this was a documentation problem, the fix will show up soon at
http://www.php.net/manual/.

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Thank you for the report, and for helping us make PHP better.