How to remove identical values ​​from php array (three methods)

It is very common to use arrays in PHP. An array is a data structure used to store multiple values. When processing large amounts of data, you may encounter situations where you need to remove duplicate data from an array. This article will introduce several common methods to achieve PHP array deduplication.

1. Use the array_unique() function

PHP provides a built-in function array_unique() to remove duplicate elements from the array. This function returns a new array containing the only element in the original array.

Sample code:

$arr = array('a', 'b', 'b', 'c', 'c', 'c');
$arr = array_unique($arr);
print_r($arr);

Output result:

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

2. Use the loop method to remove duplicates

Use a for loop to traverse the array, if the same is found element, use the unset() function to delete the element from the array. It should be noted that after deleting elements, you need to rearrange the indexes in the array. You can use the array_values() function to rearrange the array indexes.

Sample code:

$arr = array('a', 'b', 'b', 'c', 'c', 'c');
$n = count($arr);
for($i = 0; $i < $n; $i++) {
    for($j = $i + 1; $j < $n; $j++) {
        if($arr[$i] == $arr[$j]) {
            unset($arr[$j]);
        }
    }
}
$arr = array_values($arr);
print_r($arr);

Output result:

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

3. Use array_flip() and array_keys() functions to remove duplicates

This method is very simple , you only need to use the original array as a parameter of the array_flip() function, and then use the array_keys() function to return all the key names in an array to get an array without repeated elements.

Sample code:

$arr = array('a', 'b', 'b', 'c', 'c', 'c');
$arr = array_flip($arr);
$arr = array_keys($arr);
print_r($arr);

Output result:

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

Summary:

There are many ways to remove duplicate elements from an array in PHP, such as using recursion Method, use array_filter() function, etc. However, the above three methods are relatively common methods, and you can choose different methods to operate arrays according to the actual situation. It should be noted that when using the unset() function to delete elements, the array index must be reset to ensure the correctness of the array.

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