How to find the intersection of two arrays in php

Three methods: 1. Use array_intersect() to compare key values ​​to obtain the intersection, the syntax is "array_intersect(array1, array2)"; 2. Use array_intersect_key() to compare the key names to obtain the intersection, the syntax is "array_intersect_key( Array 1, Array 2)"; 3. Compare the key name and key value to obtain the intersection, the syntax is "array_intersect_assoc (array 1, array 2)".

The operating environment of this tutorial: windows7 system, PHP version 8.1, DELL G3 computer

PHP provides multiple functions to compare two To find the intersection of arrays, the following mainly introduces three commonly used functions: array_intersect(), array_intersect_assoc() and array_intersect_key().

Okay, let’s get to the topic! We have the following two arrays:

$arr1=array("a"=>"red","b"=>"green","c"=>"blue","d"=>"yellow");
$arr2=array("a"=>"orange","b"=>"green","e"=>"pink","r"=>"yellow");

Let’s use code examples to see how array_intersect(), array_intersect_assoc() and array_intersect_key() compare arrays to find intersection. .

1. array_intersect() function--compare the key values ​​​​of arrays

array_intersect($arr1,$arr2...)Function Compares only the key values ​​​​of the arrays, and then returns an intersection array that contains all the arrays $arr1 being compared, as well as any other parameter arrays $arr2...# The value in ##. (The elements in the intersection array are all elements in the compared array $arr1)

There are two key values ​​​​that exist in both the $arr1 array and the $arr2 array: "

green ” and “yellow”, and then select the intersection element from the compared array $arr1, so the output result is:

2 , array_intersect_key() function--compare the key names of the array

array_intersect_key($arr1,$arr2...)Only compare the key names of the array, and then return an intersection Array, the intersection element will be selected from the compared array $arr1 according to the key name.

Let’s take a look at the above example. There are 2 key names that exist in both the

$arr1 array and the $arr2 array: "a ” and “b”, and then select elements from the compared array $arr1 according to the key name, so the output result is:

3. array_intersect_assoc() function - compares the key names and key values ​​of the array

array_intersect_assoc($arr1,$arr2...) will compare the key names and key values ​​of the array , and then returns an intersection array.

In the above example, there is only one element with the same key name and key value in the $arr1 array and $arr2 array: "

"b"=>"green"", so The output result is:

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