I'm having trouble with the following code:

// first time through the page:
$start_time = mktime();
session_register('start_time');
...
// second time through:
$T01 = mktime() - $start_time;
session_register('T01');
...
// third time through:
$T02 = mktime() - $T01;
session_register('T02');
...

when I subtract $start_time from each consecutive $T0x timestamp I get the expected result.

However when I subtract $T01 from $T02 etc, every other result is a very large number, as if it came out negative and is being represented as an unsigned int.

Can anyone suggest what's going on?

thanks,
Shi.

are you sure you are not supposed to be using just time() instend of mktime()

thanks for the reply - the PHP book I read used mktime() so that's why I used that - when I tried changing the code to use time() I got the same result - any other ideas?

just figured it out - D'OH!

$T02 = time() - $start_time - $T01;

(only $start_time is a full timestamp, all the others are just small elapsed times)