How to compare the differences between two array keys (values) in PHP

In PHP, you can use the array_diff() function to compare the differences in the key values ​​(value) of two arrays; this function is used to compare the values ​​(value) of two (or more) arrays, and Returns a difference array containing different values, syntax "array_diff(array1,array2...);"; the difference array includes all values ​​in the compared array (array1) but not in any other parameter array (array2) .

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

Compare the difference between the two arrays, PHP provides Three methods:

• array_diff()

• array_diff_key()

• array_diff_assoc()

Among them, if you want to compare only two array key values ​​(values) and obtain different elements, you need to use the array_diff() function.

array_diff() function - only compares key values ​​(value)

array_diff() function is used to compare two (or more) ) array values ​​and returns a difference array containing different values.

• This function compares the values ​​​​of two (or more) arrays (value in key=>value) and returns a difference array, which includes all A value that is in the array being compared (array1), but not in any of the other argument arrays (array2 or array3, etc.).

array_diff(array1,array2);

Parameters	Description
array1	Required. The first array to compare with other arrays.
array2	Required. The array to compare to the first array.

• Return value: Returns a difference array that includes everything in the compared array (array1), but not in any other parameters Values ​​in an array (array2 or array3, etc.).
  

Example: Compare the key values ​​(values) of two arrays and return the difference array

<?php  
header(&#39;content-type:text/html;charset=utf-8&#39;);   
$arr1=array("a"=>"red","b"=>"green","c"=>"blue","d"=>"yellow");
$arr2=array("e"=>"red","f"=>"green","g"=>"blue");
var_dump($arr1);
var_dump($arr2);
$result=array_diff($arr1,$arr2);
echo "两个数组的不同值：";
var_dump($result);
?>

Extended knowledge: two other comparison functions

1. array_diff_key(): only compare key names (key)

array_diff_key() function is used to compare the key names of two (or more) arrays and return the difference set.

array_diff_key(array1,array2...);

Example:

<?php
header("Content-type:text/html;charset=utf-8");
$arr1=array("a"=>"red","b"=>"green","c"=>"blue","d"=>"yellow");
$arr2=array("a"=>"orange","b"=>"green","e"=>"red","r"=>"yellow");
var_dump($arr1);
var_dump($arr2);

echo "两个数组的不同值：";
$result=array_diff_key($arr1,$arr2);
var_dump($result);
?>

In the above example, there are two key names in the $arr1 array and the $arr2 array that are different. The value will be obtained based on the array $arr1. ##"c"=>"blue"" and ""d"=>"yellow"", so the output result is:

2. array_diff_assoc(): Compare key name (key) and key value (value)

array_diff_assoc() function is used to compare two (or more) The key name and key value of the array, and the difference is returned.

array_diff_assoc(array1,array2...);

Example:

<?php
header("Content-type:text/html;charset=utf-8");
$arr1=array("a"=>"red","b"=>"green","c"=>"blue","d"=>"yellow");
$arr2=array("a"=>"orange","b"=>"green","e"=>"red","r"=>"yellow");
var_dump($arr1);
var_dump($arr2);

echo "两个数组的不同值：";
$result=array_diff_assoc($arr1,$arr2);
var_dump($result);
?>

In the above example, the $arr1 array and the $arr2 array are compared. There are three different elements, and then the value "##" will be obtained based on the array $arr1. #"a"=>"red"

", ""c"=>"blue"", ""d"=>"yellow"" , so the output result is:

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