How to use php to customize an array to remove duplicate functions

When developing PHP applications, we often need to process data, and one of the most basic operations is to remove duplicate data. In order to avoid manually writing deduplication code, we can write a custom function to conveniently process the data.

The following is a simple PHP function that accepts an array as a parameter and returns a new array that does not contain duplicate elements:

function array_unique_custom($arr) {
    $unique_arr = array();
    foreach($arr as $val) {
        if(!in_array($val, $unique_arr)) {
            $unique_arr[] = $val;
        }
    }
    return $unique_arr;
}

This function uses a foreach loop to iterate through each element in the array elements. For each element $val, it first checks if it already exists in the $unique_arr array. If it doesn't exist then it adds the value to the array. Finally, the function returns this new array without duplicate elements.

Although this function is very simple, it can indeed quickly deduplicate data. The following is an example of use:

$my_array = array(1, 2, 3, 2, 4, 5, 5);
$unique_array = array_unique_custom($my_array);
print_r($unique_array);

The output result will be:

Array
(
    [0] => 1
    [1] => 2
    [2] => 3
    [3] => 4
    [4] => 5
)

This custom function is very simple and conforms to the characteristics of the PHP language, and is also very convenient to use. However, its performance may suffer for large arrays or frequent deduplication operations. Therefore, in practical applications, the optimal deduplication method needs to be selected based on the actual situation.

In the PHP language, there is a standard library function array_unique() that can also be used to remove duplicate data. This function also accepts an array as argument and returns a new array that does not contain duplicate elements. This function is implemented in a lower-level manner than a custom function, allowing for better performance in some cases.

For example, the following is a sample code using the array_unique() function:

$my_array = array(1, 2, 3, 2, 4, 5, 5);
$unique_array = array_unique($my_array);
print_r($unique_array);

The output result will be:

Array
(
    [0] => 1
    [1] => 2
    [2] => 3
    [4] => 4
    [5] => 5
)

As you can see, in the array returned by the array_unique() function Slightly different from the array returned by the custom function. This is because the array_unique() function automatically rebuilds the index of the array, while the custom function copies the index of the original array into the new array.

In practical applications, the method chosen to deduplicate data should depend on the actual situation. If high-performance deduplication is required, it is recommended to use the array_unique() function. If you are simply deduplicating a small data set, you can use a custom function.

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