I don't think you can do exactly what you're asking.
You can have a loop which will keep doing something for a minute. (while)
You can have a loop which will do something 100 times. (for)
You can mix the above so that you have a loop which will do something up to 100 times, but stop after a minute even if the 100 hasn't been reached.
But there's no way you can use the code to force that, no matter what, something will be done exactly 100 times in a minute. After all, that something might take 2 seconds to do...
If you're confident that the thing you want to do can easily be done 100 times in a minute, you could try the third option above. Pseudocode follows, cause I don't have the time to do this properly:
$starttime = time();
$i = 0;
$limit = 100;
while (($i < $limit) && ((time() - $starttime) < 60)){
//do the thing
$i++
}
This loop will stop when either you hit 100 iterations, or you exceed 60 seconds. Not exactly what you want but about as close as you're going to get.
