PHP array_udiff() function (with example)

Hey,

I've also worked with the "array_udiff()" function in PHP and I thought I'd share my experience with it. The "array_udiff()" function is really useful when you need to find the differences between multiple arrays, using your own custom comparison logic.

Essentially, the "array_udiff()" function compares the values of the arrays by using a user-defined callback function. This callback function is responsible for implementing the comparison logic and should return a negative, positive, or zero value to determine the order of elements.

In my project, I had an array of objects, and I wanted to find the objects that were unique among multiple arrays based on a specific property. Here's a simplified example to demonstrate how it can be used:

php
class User {

    public $id;

    public $name;



    public function __construct($id, $name) {

        $this->id = $id;

        $this->name = $name;

    }

}



function compareUsers($user1, $user2) {

    return $user1->id - $user2->id;

}



$users1 = [

    new User(1, 'John'),

    new User(2, 'Alice'),

    new User(3, 'Bob')

];



$users2 = [

    new User(2, 'Alice'),

    new User(4, 'Jane')

];



$result = array_udiff($users1, $users2, 'compareUsers');

Hey there,

I've used the "array_udiff()" function in my PHP project before, so I can definitely help explain it to you. The "array_udiff()" function is really handy when you need to compare and find the differences between multiple arrays, using your own custom logic to determine the comparison.

The key to understanding the "array_udiff()" function lies in the callback function you provide. This callback function is responsible for comparing the values of the arrays and determining their uniqueness. It takes two arguments, let's call them "$a" and "$b", which are the values being compared.

In the callback function, you need to define your own comparison logic by implementing a comparison algorithm. The function should return a negative integer if "$a" is less than "$b", a positive integer if "$a" is greater than "$b", or zero if they are equal. This allows "array_udiff()" to correctly identify the differences between the arrays.

Let me give you a simple example to illustrate how it works. Let's say we have two arrays: $array1 and $array2. We want to find the elements present in $array1 that are not present in $array2. We can use "array_udiff()" for that:

php
function compareValues($a, $b) {

    return $a - $b; // Custom comparison logic - subtracting values for simplicity

}



$array1 = [1, 2, 3, 4, 5];

$array2 = [2, 4, 6];



$result = array_udiff($array1, $array2, 'compareValues');

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