Calculate the time needed to run a certain function

I that possible? for eg. if I want to test if str_replace() is faster 开发者_开发知识库that preg_replace() ?

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The easy way:

$time = microtime(true); // time in Microseconds

// Your code here

echo (microtime(true) - $time) . ' elapsed';

The hard(er) way: Use a code profiler to see exactly how much time your methods will take.

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You can run the same line 10,000 times (or more) in your script, and use microtime(true) to tell the time it took.

Reference: microtime()

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I found this answer by 'bisko' in this thread.

$start = microtime(true);

for (...) { .... }

$end = microtime(true);

echo ($end - $start).' seconds';

The for-loop can be replaced by whatever you want to time.