How to remove duplicate elements from array in PHP

In PHP, array is a very powerful data type used to store and operate a set of data. However, sometimes we need to remove duplicate elements from an array. This article will introduce how to remove duplicate elements from an array in PHP.

1. Use the array_unique() function

We can use the array_unique() function in PHP to remove duplicate elements from the array. This function will return a new array containing all the distinct elements in the original array.

The following is a sample code using the array_unique() function:

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

The above code will output the following:

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

2. Use loops to remove duplicates

In addition to using the array_unique() function, we can also use loops to remove duplicate elements in the array. We can use a foreach loop to iterate through each element in the array and compare it to a new array.

The following is a sample code using loop deduplication:

$numbers = array(1, 2, 2, 3, 3, 3, 4, 4, 4, 4);
$unique_numbers = array();
foreach ($numbers as $number) {
    if (!in_array($number, $unique_numbers)) {
        $unique_numbers[] = $number;
    }
}
print_r($unique_numbers);

The above code will output the following:

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

3. Use array_flip() and array_values() functions

Another method is to use the array_flip() and array_values() functions. First, we use the array_flip() function to swap the keys and values ​​in the array. This way, duplicate values ​​are converted into keys. Then, we use the array_values() function to get all the values ​​in the array.

The following is sample code using the array_flip() and array_values() functions:

$numbers = array(1, 2, 2, 3, 3, 3, 4, 4, 4, 4);
$unique_numbers = array_values(array_flip($numbers));
print_r($unique_numbers);

The above code will output the following:

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

Summary

In PHP, we can use array_unique() function, loops and array_flip() and array_values() functions to remove duplicate elements from an array. Which method you choose depends on your specific needs and personal preferences. No matter which method we choose, all these methods can help us handle duplicate elements in arrays easily, making our code more concise and efficient.

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