Array Functions
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PHP array_diff() Function

Topic: PHP Array ReferencePrev|Next

Description

The array_diff() function compares the values of two or more arrays and returns the differences.

The following table summarizes the technical details of this function.

Return Value: Returns an array containing all the elements from array1 that are not present in any of the other arrays.
Version: PHP 4.0.1+

Syntax

The basic syntax of the array_diff() function is given with:

array_diff(array1, array2, ...);

The following example shows the array_diff() function in action.

<?php
// Sample arrays
$array1 = array("apple", "ball", "cat", "dog", "elephant");
$array2 = array("alligator", "dog", "elephant", "lion", "cat");

// Computing the difference
$result = array_diff($array1, $array2);
print_r($result);
?>

Parameters

The array_diff() function accepts the following parameters.

Parameter Description
array1 Required. Specifies the array to compare from.
array2 Required. Specifies an array to compare against.
... Optional. Specifies more arrays to compare against.

More Examples

Here're some more examples showing how array_diff() function actually works:

The following example shows how to use this function to compare an array against two other arrays.

<?php
// Sample arrays
$array1 = array("apple", "ball", "cat", "dog");
$array2 = array("cat", "lion", "tiger");
$array3 = array("apple", "banana");

// Computing the difference
$result = array_diff($array1, $array2, $array3);
print_r($result);
?>

Two elements are considered equal if their string representation are same, i.e., (string) $elem1 === (string) $elem2. Let's take a look at the following example:

<?php
// Sample arrays
$array1 = array(1, 2, 5, 7, 11);
$array2 = array(0, "1", 2, 4, "07", 10);

// Computing the difference
$result = array_diff($array1, $array2);
print_r($result);
?>

You can also use associative arrays, however the keys are not considered in the comparison.

<?php
// Sample arrays
$array1 = array("a"=>"red", "b"=>"green", "c"=>"blue", "d"=>"yellow");
$array2 = array("x"=>"black", "y"=>"blue", "z"=>"red");

// Computing the difference
$result = array_diff($array1, $array2);
print_r($result);
?>
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