How to remove duplicate elements from an array in php

php method to remove duplicate elements in an array: 1. Use the "array_unique()" function to remove duplicate data in the array; 2. Traverse through a foreach loop and define a new array to store non-duplicate data Method to achieve deduplication; 3. Use the array_flip() and array_keys() functions to get the deduplicated array; 4. Use the array_filter() function to deduplicate the original array by using this function in combination with an anonymous function.

Operating system for this tutorial: Windows 10 system, PHP version 8.1.3, Dell G3 computer

php removes duplicate elements from an array Method

Method 1: Use the array_unique() function

The array_unique() function in php can be used to remove duplicate data from the array. This function accepts an array as argument and returns a new array that does not contain duplicate values.

Sample code:

$arr = array(1, 2, 2, 3, 4, 4);
$arr_unique = array_unique($arr);
print_r($arr_unique);

Output result:

Array
(
    [0] => 1
    [1] => 2
    [3] => 3
    [4] => 4)

Method 2: Use foreach loop to traverse

In addition to using array_unique() In addition to functions, we can also achieve deduplication through loop traversal. The specific steps are as follows:

Define a new array to store unique data. Iterate over the original array, comparing each element to each element in the new array one by one, skipping if there are duplicates, and adding the element to the new array if there are no duplicates.

Sample code:

$arr = array(1, 2, 2, 3, 4, 4);
$new_arr = array();
foreach ($arr as $value) {
    if (!in_array($value, $new_arr)) {
        $new_arr[] = $value;
    }
}
print_r($new_arr);

Output result:

Array
(
    [0] => 1
    [1] => 2
    [3] => 3
    [4] => 4)

Method 3: Use array_flip() and array_keys() functions

The array_flip() function in php can be used to swap keys and values ​​in an array. By exchanging the key values ​​of the original array and then using the array_keys() function to obtain the keys, the deduplicated array can be obtained.

Sample code:

$arr = array(1, 2, 2, 3, 4, 4);
$new_arr = array_keys(array_flip($arr));
print_r($new_arr);

Output result:

Array
(
    [0] => 1
    [1] => 2
    [2] => 3
    [3] => 4)

Method 4: Use array_filter() function

array_filter in php () function can be used to filter elements in an array. We can deduplicate the original array by using this function combined with an anonymous function.

Sample code:

$arr = array(1, 2, 2, 3, 4, 4);
$new_arr = array_filter($arr, function ($value) {
    static $data = [];
    if (in_array($value, $data)) {
        return false;
    } else {
        $data[] = $value;
        return true;
    }
});
print_r($new_arr);

Output result:

Array
(
    [0] => 1
    [1] => 2
    [3] => 3
    [4] => 4)

Summary:

The methods to remove duplicate data in an array in PHP are There are many, and the methods introduced above are just a few of them. We can choose appropriate deduplication methods based on different needs and data structures to improve the efficiency and stability of the program.

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