How to detect if an array is a subset of another array via PHP

As the title says, this article will introduce to you how to determine whether an array is a subset of another array through PHP. What does subset mean? Although everyone may know it, I will still introduce the concept of subset to you by the way~

The introduction to subset is as follows:

Subset is actually a mathematical concept : If any element of set A is an element of set B, then set A is called a subset of set B.

After briefly understanding what a subset is, let’s go directly to the code:

The PHP code is as follows:

<?php
// 定义两个数组
$array1 = array(&#39;a&#39;,&#39;1&#39;,&#39;2&#39;,&#39;3&#39;,&#39;4&#39;);
$array2 = array(&#39;a&#39;,&#39;3&#39;);

if (array_intersect($array2, $array1) === $array2) {
    echo "它是一个子集";
} else {
    echo "它不是一个子集";
}

Output:

它是一个子集

In this code, we define two arrays.

The first array is very large, with 6 values;

The second array is very small, with 2 values;

And when we search for the second array Is it a subset of the first array, which means that all values ​​of the second array should be present in the first array.

Here we will introduce to you a functionarray_intersect()Function:

array_intersect()The function is used to compare two (or more Key values ​​of multiple) arrays and return the intersection.

This function compares the key values ​​​​of two (or more) arrays and returns the intersection array, which includes everything in the compared array (array1) and any other parameter arrays ( key values ​​in array2 or array3 etc.).

The return value of this function is: return the intersection array, which includes all key values ​​in the compared array (array1) and in any other parameter array (array2 or array3, etc.) .

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