How to remove duplicates from php array? Brief analysis of three methods

When developing web applications, it is often necessary to use arrays to store data. Sometimes we need to deduplicate these arrays for subsequent processing and analysis. This article will introduce several array deduplication methods in PHP.

Method 1: Use the array_unique function

PHP provides a built-in function array_unique to remove duplicate values ​​​​in the array. The usage is very simple, you just need to pass in the array to be deduplicated.

Sample code:

<?php
$arr = array(1, 2, 2, 3, 4, 4, 5);
$result = array_unique($arr);
print_r($result);
?>

Output result:

Array
(
    [0] => 1
    [1] => 2
    [3] => 3
    [4] => 4
    [6] => 5
)

Method 2: Use loop traversal

Another deduplication method is to use a loop to traverse the array, Just delete duplicate values ​​when encountered.

Sample code:

<?php
$arr = array(1, 2, 2, 3, 4, 4, 5);
for ($i = 0; $i < count($arr); $i++) {
    for ($j = $i + 1; $j < count($arr); $j++) {
        if ($arr[$i] == $arr[$j]) {
            array_splice($arr, $j, 1);
        }
    }
}
print_r($arr);
?>

Output result:

Array
(
    [0] => 1
    [1] => 2
    [2] => 3
    [3] => 4
    [4] => 5
)

Method 3: Use array_flip and array_keys functions

This method uses PHP array keys that cannot be repeated Features, deduplication can be achieved by flipping the keys and values ​​of the array, and then using the array_keys function to return the key value.

Sample code:

<?php
$arr = array(1, 2, 2, 3, 4, 4, 5);
$temp = array_flip($arr);
$result = array_keys($temp);
print_r($result);
?>

Output result:

Array
(
    [0] => 1
    [1] => 2
    [2] => 3
    [3] => 4
    [4] => 5
)

Summary

This article introduces three commonly used array deduplication methods in PHP, using array_unique function, looping through and using array_flip and array_keys functions. Different methods can be chosen for different scenarios and needs. Which method to choose depends on the actual situation, and developers need to make a choice based on business needs and performance requirements.

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