This is interesting to know, but my suggestion is to do whatever you feel is most readable/maintainable. I did not assign it to anything, for an assignment would be an additional time-cost.) // explode separatelyĪs you can see from the results table, it then becomes the slowest method of the three. (I only ran strlen($val) and ignored its output. That's subject to debate, but I was only trying to make a general point. I used strlen($val), thinking it would be a relatively similar execution time. I added a bonus to the chart where I run method 1) with a function call in the loop. In terms of number of function calls, explode()ing really tops tokenizing. Working on such a small scale, I believe that's due to the call stack overhead of making a function call to strtok() every iteration.

Surprisingly, tokenizing is a bit slower than explicitly iterating a declared array.When you explode() inline without pre-assignment, it's a fair bit slower for some reason.If you're iterating over something huge, time difference is relatively minor but memory usage could be different by an order of magnitude!.In the big picture, any of these methods is sufficiently fast for a list of 'reasonable size' (few hundred or few thousand).Looks like some assumptions were disproven. Printf('Total time: %s s ', $timeElapsed) įoreach (explode(',', $listStr) as $val) Printf('Memory used: %s kB ', memory_get_peak_usage()/1024) probably both quicker and much smaller memory footprint Ok - I think that because the exploded string yields a simple array the inner foreach loop needs only to check if the current array member is equal to the cid field for the current record.probably identical to #1 or #3, not sure which.probably consume more memory due to assignment If the limit is positive, the explode() function returns an array with limit elements where the last element containing the rest of the string.explode and assign before entering the loop.I figured there were three main ways to approach this. I could make an educated guess, but let's try it out!

Php explode foreach loop