Remove Duplicate Values from Array PHP

Through this tutorial, we will learn how to remove duplicate elements/values from an array without using any function in PHP and also will learn how to remove elements/values from an array using inbuilt function array_unique() and array_flip() in PHP.

How to remove duplicate values from an array in PHP?

Here are some methods:

• Method 1: Using array_unique()
• Method 2: Using a loop
• Method 3: Using array_flip() and array_keys()

Method 1: Using array_unique()

The simplest way to remove duplicate values from an array in PHP is to use the built-in function array_unique(). This function takes an array as input and returns a new array with all duplicate values removed. Here’s an example:

<?php
$array = array(1, 2, 2, 3, 3, 3);
$unique_array = array_unique($array);
print_r($unique_array);
?>

The given code is written in PHP, and it creates an array named $array with the values 1, 2, 2, 3, 3, 3.

Then, the code uses the PHP built-in function array_unique() to remove any duplicate values from the array. The unique values are then stored in a new array named $unique_array.

Finally, the print_r() function is used to display the contents of the $unique_array.

So, the output of this code will be:

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

Here, the duplicate values of 2 and 3 have been removed from the original array and only unique values 1, 2, and 3 are displayed in the $unique_array.

Method 2: Using a loop

Another way to remove duplicate values from an array is to use a loop. We can iterate over the array and check if each value is already present in a new array. If the value is not present, we add it to the new array. Here’s an example:

<?php
$array = array(1, 2, 2, 3, 3, 3);
$unique_array = array();
foreach($array as $value) {
    if(!in_array($value, $unique_array)) {
        $unique_array[] = $value;
    }
}
print_r($unique_array);
?>

Output:

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

Method 3: Using array_flip() and array_keys()

Another way to remove duplicate values from an array is to use the array_flip() and array_keys() functions. We can flip the array, so that the values become keys, and then use the array_keys() function to get the keys. This will give us a new array with all duplicate values removed. Here’s an example:

<?php
$array = array(1, 2, 2, 3, 3, 3);
$flipped_array = array_flip($array);
$unique_array = array_keys($flipped_array);
print_r($unique_array);
?>

Output:

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

This shows that the original array $array contained three unique values: 1, 2, and 3.

Conclusion

In this article, we have explored various ways to remove duplicate values from an array in PHP.

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