PHP array learning: how to compare two arrays and find the intersection

In the previous article "PHP String Learning: Comparing Two Strings", we introduced the method of comparing two strings. Strings and arrays are both important data types in PHP. We not only need to understand how to compare strings, but also how to compare arrays. Let me introduce to you the method of comparing arrays and returning the same elements (intersection).

First of all, we need to know that PHP provides multiple functions to compare two arrays and find the intersection. This article 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 Returns an intersection array. The intersection elements 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:

Okay, that’s all. If you want to know anything else, you can click this. → →

php video tutorial

Finally, I would like to recommend a free video tutorial on PHP arrays:

PHP function array array function video explanation, come and learn!

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