How to remove duplicates from php arrays (three methods)

In PHP, array is a very common data type, which can be used to store a series of related data, such as name, age, gender, etc. But in actual development, we often encounter a problem, that is, how to remove duplicate elements in an array? This article is going to introduce some common methods to implement PHP array deduplication.

Method 1: Use array_unique() function

PHP has a built-in convenient function array_unique(), which can be used to remove duplicate elements from an array. This function can accept an array as a parameter and then return a new array. The elements in the new array are independent elements in the original array.

The following is a sample code:

<?php
$array = array("a", "b", "b", "c", "c", "c");
$new_array = array_unique($array);
print_r($new_array);
?>

The output result is as follows:

Array
(
    [0] => a
    [1] => b
    [3] => c
)

Method 2: Use loop traversal

Another common method is to use a loop Iterate over the original array and add unique elements to a new array.

The following is the sample code:

<?php
$array = array("a", "b", "b", "c", "c", "c");
$new_array = array();

foreach ($array as $value) {
    if (!in_array($value, $new_array)) {
        $new_array[] = $value;
    }
}

print_r($new_array);
?>

The output result is also:

Array
(
    [0] => a
    [1] => b
    [3] => c
)

Method 3: Use the array_flip() function

PHP’s array_flip() function You can reverse the keys and values ​​of an array and return a new array. Since the keys of the array cannot be repeated, when there are duplicate values ​​in the original array, only one will be retained in the reversed array.

Then take out the key name (the value in the original array) from the new array to get a non-duplicate array.

The following is the sample code:

<?php
$array = array("a", "b", "b", "c", "c", "c");
$new_array = array_flip($array);

print_r(array_keys($new_array));
?>

The output result is also:

Array
(
    [0] => a
    [1] => b
    [2] => c
)

Summary

In this article, we introduced three common Methods to achieve deduplication of PHP arrays are to use the array_unique() function, use loop traversal, and use the array_flip() function. These three methods are relatively simple, and developers can choose the appropriate method to achieve array deduplication according to the specific situation.

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