Two ways to learn PHP using the array_diff() function to compare array differences

This article will briefly introduce the array_diff() function in PHP to compare the difference between two arrays. Interested friends can learn about it.

There is an array_diff() in the PHP built-in function: it means comparing the key values of two arrays and returning the difference.

The following is to implement the difference set through array traversal:
First there are two different arrays $arr_1, $arr_2:
The first method:

function fun($arr_1,$arr_2) { foreach ($arr_1 as $key => $val) { $bool = false; foreach ($arr_2 as $k => $v) { if($bool = ($val == $v)) { break; } } if(!$bool) { $diff[$key] = $val; } } }

Although this method can realize the difference between arrays, if the array length reaches a certain length, the efficiency is not optimistic.

Two methods:

foreach ($arr_1 as $key => $val) { if(in_array($val,$arr_2)) { unset($arr_1[$key]); } }

This method is said to be comparable to array_diff() on other blogs.

Three ways:
After inverting the key value of the arr_2 array through "array_flip();", determine whether the value in the arr_1 array is in the key of arr_2

$arr_2 = array_flip($arr_2);foreach ($arr_1 as $key => $val) { if(isset($arr_2[$val])) { unset($arr_1[$key]); } }

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