note 37176 modified in control-structures.for by vrana

According to my tests, the "do...while" control structure actually seems to be ~40% faster than the "for" control structure. At least using PHP v4.0.6 on a few fairly modern Linux machines. I used a the getmicrotime function as defined at http://www.php.net/microtime I tested the following 5 scenarios, including two different ways of calling a "for" loop. The less ordinary way to call "for", I'll call "altfor". Here are the code scenarios for different ways from counting from 0->($num-1), in my case $num = 10000: <?php // 'altfor': $a=0; for (; $a<$num;) { $a++;} // 'for': for ($a=0; $a<$num; $a++) {} // 'foreach': foreach (range(0,$num-1) as $a ) {} // 'while': $a = 0; while ($a < $num) {$a++;} // 'do': $a = 0; do {} while (++$a < $num); ?> Each scenario is called in random order, and here is a typical result: Average times for 100 iterations of each loop: altfor, do, for, foreach, while. All loops are incremented from 0 to 9999. altfor: 0.036882833242416 seconds, 138.25 percent of ~ 0.0267 seconds do: 0.026678282022476 seconds, 100.00 percent of ~ 0.0267 seconds for: 0.037308998107910 seconds, 139.85 percent of ~ 0.0267 seconds foreach: 0.064857139587402 seconds, 243.11 percent of ~ 0.0267 seconds while: 0.036508817672729 seconds, 136.85 percent of ~ 0.0267 seconds ...so to be clear, I ran "for", et all, from 0->9999. This was done 100 times. Above are the average times for those 100 tests of loops of 10,000. I have run my script multiple time on several different Linux systems here at my work. All w/ similar results... --was-- According to my tests, the "do...while" control structure actually seems to be ~40% faster than the "for" control structure. At least using PHP v4.0.6 on a few fairly modern Linux machines. I used a the getmicrotime function as defined at http://www.php.net/microtime I tested the following 5 scenarios, including two different ways of calling a "for" loop. The less ordinary way to call "for", I'll call "altfor". Here are the code scenarios for different ways from counting from 0->($num-1), in my case $num = 10000: // 'altfor': $a=0; for (; $a<$num;) { $a++;} // 'for': for ($a=0; $a<$num; $a++) {} // 'foreach': foreach (range(0,$num-1) as $a ) {} // 'while': $a = 0; while ($a < $num) {$a++;} // 'do': $a = 0; do {} while (++$a < $num); Each scenario is called in random order, and here is a typical result: Average times for 100 iterations of each loop: altfor, do, for, foreach, while. All loops are incremented from 0 to 9999. altfor: 0.036882833242416 seconds, 138.25 percent of ~ 0.0267 seconds do: 0.026678282022476 seconds, 100.00 percent of ~ 0.0267 seconds for: 0.037308998107910 seconds, 139.85 percent of ~ 0.0267 seconds foreach: 0.064857139587402 seconds, 243.11 percent of ~ 0.0267 seconds while: 0.036508817672729 seconds, 136.85 percent of ~ 0.0267 seconds ...so to be clear, I ran "for", et all, from 0->9999. This was done 100 times. Above are the average times for those 100 tests of loops of 10,000. I have run my script multiple time on several different Linux systems here at my work. All w/ similar results... http://php.net/manual/en/control-structures.for.php