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 the array_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 use array_flip() and array_keys() functions.

array_flip() The function swaps the keys and values ​​in the array. The array_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 the array_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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