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How to remove duplicate values from array using PHP ?

  • Last Updated : 07 Oct, 2021

In this article, we will discuss how to remove duplicate elements from an array in PHP. We can get the unique elements by using array_unique() function. This function will remove the duplicate values from the array.

Syntax:

array array_unique($array, $sort_flags)

Note: The keys of the array are preserved i.e. the keys of the not removed elements of the input array will be the same in the output array.

Parameters: This function accepts two parameters that are discussed below:

  • $array: This parameter is mandatory to be supplied and it specifies the input array from which we want to remove duplicates.
  • $sort_flags: It is optional parameter. This parameter may be used to modify the sorting behavior using these values:
    • SORT_REGULAR: This is the default value of the parameter $sort_flags. This value tells the function to compare items normally (don’t change types).
    • SORT_NUMERIC: This value tells the function to compare items numerically.
    • SORT_STRING: This value tells the function to compare items as strings.
    • SORT_LOCALE_STRING: This value tells the function to compare items as strings, based on the current locale.

Return Value: The array_unique() function returns the filtered array after removing all duplicates from the array.



Example: PHP program to remove duplicate values from the array.

PHP




<?php
  
// Input Array
$a = array("red", "green", "red", "blue");
  
// Array after removing duplicates
print_r(array_unique($a));
  
?>
Output
Array
(
    [0] => red
    [1] => green
    [3] => blue
)

Example 2: PHP program to remove duplicate elements from an associative array.

PHP




<?php
  
// Input array
$arr = array(
      "a" => "MH"
      "b" => "JK"
      "c" => "JK"
      "d" => "OR"
);
  
// Array after removing duplicates
print_r(array_unique($arr));
  
?>
Output
Array
(
    [a] => MH
    [b] => JK
    [d] => OR
)



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