Remove duplicates from array PHP

In this post, you will learn how to remove duplicates from an array using the PHP programming language.

Sometimes in the development process, we may face a situation where we need to filter arrays to remove duplicates. There are lots of ways to remove the duplicate values. But, PHP provides a simple in-built function, array_unique() to remove the duplicate values from an array.

Likewise, according to this function, two elements are viewed as equivalent if and only if (string) $element1 === (string) $element2, i.e., when the string representation of the elements is the same.

Syntax of array_unique()

array_unique(array, sorttype)

Here, the array is a required parameter, and sorttype is an optional parameter. It specifies how to compare the array elements/items. The possible values are-

• SORT_STRING- Compare items as strings
• SORT_REGULAR- Compare items normally
• SORT_NUMERIC- Compare items numerically
• SORT_LOCALE_STRING- Compare items as strings

It takes a SORT_STRING value by default, which compares items as strings. This function returns a new array without duplicate values. If two or more array values are similar, the first appearance will be kept and the other will be eliminated.

PHP remove duplicates from array

In the given PHP program, we have defined the repeated values one-dimensional array. We have passed this array to the array_unique() function to remove the duplicate values.

<?php
 $fruits = array('Apple', 'Orange', 'Apple', 'Banana', 'Kiwi', 'Orange');
 $result = array_unique($fruits);
 print_r($result);
?>

Array ( [0] => Apple [1] => Orange [3] => Banana [4] => Kiwi )

PHP remove duplicates from associative Array

In the given PHP program, we remove the duplicate values from associative array. In this, the key and value of the first appearance will be retained.

<?php
	$state = ['a' => 'JH', 
        'b' => 'DL',
        'c' => 'HR', 
        'f' => 'MH', 
        'd' => 'DL', 
        'e' => 'JH', 
        'g' => 'JK',
        'h' => 'UP'];
  $output = array_unique($state);
  print_r($output);
?>

Array
(
    [a] => JH
    [b] => DL
    [c] => HR
    [f] => MH
    [g] => JK
    [h] => UP
)

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