PHP array_search and in_array function efficiency issues

Problem

In an interface, it was found that it was very time-consuming. After investigating the reason, it was found that when array_search searches for the key of an element in an array, the efficiency increases as the array becomes larger, and the time-consuming increases. Especially for large arrays, it is very time-consuming. This problem also exists in the function in_array.

Solution

After using array_flip, use isset instead of in_array function, and use $array[key] instead of array_search. This can solve the time-consuming problem of large arrays

The following are the notes I copied from the php official website. You can observe the difference in efficiency between the two methods

Original website: https://www.php.net/manual/en/function. in-array.php

If you're working with very large 2 dimensional arrays (eg 20,000+ elements) it's much faster to do this...

$needle = 'test for this'; $flipped_haystack = array_flip($haystack); if ( isset($flipped_haystack[$needle]) ) { print "Yes it's there!"; }

I had a script that went from 30+ seconds down to 2 seconds (when hunting through a 50,000 element array 50,000 times). Remember to only flip it once at the beginning of your code though!

Correction

Someone commented that array_flip is more efficient than in_array and array_search. After doing some experiments, it is true. This is something I didn't consider originally. This solution is only valid if the in_array and array_search functions are used multiple times. Below are the results of my own experiments. Thanks @puppet for pointing out the problem

        

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Result:

原始方法:0.0010008811950684 新方法:0.0069980621337891

Loop 5000 times

$array = array(); for ($i=0; $i<200000; $i++){ ##随机字符串 $array[$i] = get_rand().$i; } $str = $array[199999]; $time1 = microtime(true); for ($i=0; $i<5000; $i++){ array_search($str, $array); } $time2 = microtime(true); echo '原始方法:'.($time2-$time1)."\n"; $time3 = microtime(true); $new_array = array_flip($array); for ($i=0; $i<5000; $i++){ isset($new_array[$str]); } $time4 = microtime(true); echo '新方法:'.($time4-$time3);

Result:

原始方法:2.9000020027161 新方法:0.008030891418457

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