How to compare two arrays for equality in php

Comparison steps: 1. Use the "array_diff_assoc($arr1,$arr2)" statement to compare the key names and key values ​​of the two arrays and return a difference array; 2. Use "difference array ==[] " statement determines whether the difference array is an empty array. If it is an empty array, it means that the two arrays being compared are equal, otherwise they are not equal.

The operating environment of this tutorial: Windows 7 system, PHP version 8.1, DELL G3 computer

In php, you can use the array Difference set to determine whether two arrays are equal.

• If the difference between the two arrays is empty, then there are no different elements in the two arrays, that is, the two arrays are equal

• If the difference set of the two arrays is not empty, then there are different elements in the two arrays, that is, the two arrays are not equal.

So what about the difference set of the arrays? Get Ni? You can use the array_diff_assoc() function.

• array_diff_assoc() is used to compare the key names and key values ​​of two (or more) arrays and return the difference array.

Only two arrays are equal if their array key names and key values ​​are equal.

Implementation steps:

1. Use array_diff_assoc() to obtain the array difference set

<?php 
header("content-type:text/html;charset=utf-8");
$arr1=array("a"=>"red","b"=>"green","c"=>"blue","d"=>"yellow");
$arr2=array("a"=>"red","b"=>"green","c"=>"blue");
$arr3=array("a"=>"red","b"=>"green","c"=>"blue");
$diff1=array_diff_assoc($arr1,$arr2);
var_dump($diff1);
$diff2=array_diff_assoc($arr2,$arr3);
var_dump($diff2);
?>

It can be seen from the output that there is a difference set between $arr1 and $arr2, but there is no difference set between $arr2 and $arr3

2. Determine whether the difference set array is an empty array

if($diff1==[]){
	echo "两数组相等<br>";
}
else{
	echo "两数组不相等<br>";
}

Because the difference arrays of $arr1 and $arr2 are not empty arrays, so they are not equal

if($diff2==[]){
	echo "两数组相等<br>";
}
else{
	echo "两数组不相等<br>";
}

Because $arr2 and $arr3 are empty arrays, Therefore equal.

Extension: Encapsulate the code:

<?php 
header("content-type:text/html;charset=utf-8");
function f($arr1,$arr2){
	$diff1=array_diff_assoc($arr1,$arr2);
	if($diff1==[]){
		echo "两数组相等<br>";
	}
	else{
		echo "两数组不相等<br>";
	}
}

$arr1=array("a"=>"red","b"=>"green","c"=>"blue","d"=>"yellow");
$arr2=array("a"=>"red","b"=>"green","c"=>"blue");
$arr3=array("a"=>"red","b"=>"green","c"=>"blue");

f($arr1,$arr2);

f($arr2,$arr3);
?>

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