How to convert array to unique list in PHP

There are many ways to convert an array into a unique list in PHP: array_unique() function: associate the values in the array with keys, and select the first value corresponding to the key as a unique element. The array_flip() and array_keys() functions: first swap the array key values, and then return a new array containing all keys. Custom functions: For more complex cases, custom functions can be used to handle duplicate values in an array.

How to convert an array into a distinct list in PHP

When processing data, it is often necessary to convert an array into a distinct list Duplicate list. There are several ways to achieve this in PHP.

array_unique() function

array_unique()function is the simplest way to convert an array into a unique list. It associates the values in the array with keys and selects the first value corresponding to the key as a unique element.

$array = [1, 2, 3, 1, 2, 4]; $uniqueArray = array_unique($array);

Practical case

Consider an array that saves the product ID in the order:

$orderIds = [100, 101, 102, 100, 103];

Use thearray_unique()function, We can filter duplicate order IDs:

$uniqueOrderIds = array_unique($orderIds); var_dump($uniqueOrderIds);

Output:

array(5) { [0]=> int(100) [1]=> int(101) [2]=> int(102) [3]=> int(103) }

array_flip() and array_keys() functions

Another way is to usearray_flip()andarray_keys()functions.

array_flip()The function swaps the keys and values in the array. Thearray_keys()function returns a new array containing all the keys in the array.

$array = [1, 2, 3, 1, 2, 4]; $uniqueArray = array_keys(array_flip($array));

This will produce the same results as thearray_unique()function.

Custom function

For more complex scenarios, you can also write your own custom function to handle duplicate values in the array.

function removeDuplicates($array) { $uniqueValues = []; foreach ($array as $value) { if (!in_array($value, $uniqueValues)) { $uniqueValues[] = $value; } } return $uniqueValues; }

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