How to delete duplicate array elements in php

With the popularity of the Internet, PHP, as a widely used programming language, has gradually become one of the most commonly used languages ​​​​by programmers. As the amount of data continues to increase, we need to deduplicate the data in order to reduce the amount of data and improve data processing efficiency. How to remove duplicate array elements in php? Next let’s learn more about it.

In PHP, some powerful programming tools are provided that can be used to delete duplicate elements in arrays. Some of these methods are relatively simple, but some require some more advanced technical knowledge. Below we will introduce in detail four common methods of deleting duplicate elements in arrays for your reference and learning.

Method 1: Use the array_unique function

The array_unique() function is a deduplication method that comes with PHP, which can remove duplicate elements from the array and return a new array.

Sample code:

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

Output result:

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

It can be seen that in the original array, 1 and 3 have been removed, and the remaining elements are stored in the original order in the new array.

Method 2: Use loop traversal method

In PHP, you can also use for loop or foreach loop to remove duplicate elements in the array. This method is more flexible and suitable for handling some special situations. The following is a sample code based on a for loop:

$array = array(1, 2, 1, 3, 4, 3);
$new_array = array();
for ($i = 0; $i < count($array); $i++) {
    if (!in_array($array[$i], $new_array)) {
        $new_array[] = $array[$i];
    }
}
print_r($new_array);

Output result:

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

It can be seen that the result after deduplication using this method is consistent with the result using the array_unique() function.

Method 3: Use the array_flip function

The array_flip() function is a key-value exchange function in PHP. It can quickly use the repeated values ​​​​in the original array as the keys of the new array, so as to Heavy.

Sample code:

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

Output result:

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

You can see that in the new array, all key values ​​​​are unique, thus achieving deduplication the goal of. However, this method only works when the attribute values ​​in the array are strings or integers.

Method 4: Use the array_reduce function

The array_reduce() function is also a commonly used function in PHP. You can perform a series of calculations on all elements in the array by specifying a custom function. .

Sample code:

$array = array(1, 2, 1, 3, 4, 3);
$new_array = array_reduce($array, function($result, $value) {
    if (!in_array($value, $result)) {
        $result[] = $value;
    }
    return $result;
}, array());
print_r($new_array);

Output result:

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

As you can see, this method uses the custom function of array_reduce() to remove duplicate elements from the original array. The same results as other methods were obtained.

To sum up, the four PHP methods given above for deleting duplicate array elements are all feasible, and developers can choose the applicable method according to actual needs. At the same time, when performing complex array operations, you must also pay attention to issues such as data type and array length to avoid other abnormal situations.

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