PHP RFC: array_find

• Version: 1.0.0
• Date: 2024-04-07
• Author: Joshua Rüsweg, josh@php.net
• Status: Under Discussion
• First Published at: https://wiki.php.net/rfc/array_find

This RFC proposes the addition of two new functions array_find and array_find_key, which return the first element for which a predicate callback returns true.

There are currently lots of functions in PHP for modifying or filtering arrays. However, there is no simple function to search an array with a callback and return the first result. Implementing this in userland is relatively simple (either via a loop or via array_filter combined with reset), but the function is often required, so this type of function is often built [1]. Therefore there is a reason to include this function as standard with the next PHP version. In addition, the implementation of the function is similar to array_filter and relatively trivial to implement, so the maintenance effort should be low.

This RFC proposes to add two new function, array_find and array_find_key.

function array_find(array $array, callable $callback): mixed {
    foreach ($array as $key => $value) {
        if ($callback($value, $key)) {
            return $value;
        }
    }
 
    return null;
}

array $array

The array that should be searched.

callable $callback

The callback function to call to check each element. The first parameter contains the value, the second parameter contains the corresponding key. If this function returns true, the value is returned from array_find and the callback will not be called for further elements.

The function returns the first array value for which the $callback returns true. If no matching entry is found, the function returns NULL.

$array = [
    'a' => 'dog',
    'b' => 'cat',
    'c' => 'cow',
    'd' => 'duck',
    'e' => 'goose',
    'f' => 'elephant'
];
 
// Find the first animal with a name longer than 4 characters.
var_dump(array_find($array, function (string $value) {
    return strlen($value) > 4;
})); // string(5) "goose"
 
// Find the first animal whose name begins with f. 
var_dump(array_find($array, function (string $value) {
    return str_starts_with($value, 'f'); 
})); // NULL
 
// Find the first animal where the array key is the first symbol of the animal.
var_dump(array_find($array, function (string $value, $key) {
   return $value[0] === $key;
})); // string(3) "cow"
 
// Find the first animal where the array key matching a RegEx.
var_dump(array_find($array, function ($value, $key) {
   return preg_match('/^([a-f])$/', $key);
})); // string(3) "dog"

function array_find_key(array $array, callable $callback): mixed {
    foreach ($array as $key => $value) {
        if ($callback($value, $key)) {
            return $key;
        }
    }
 
    return null;
}

array $array

The array that should be searched.

callable $callback

The callback function to call to check each element. The first parameter contains the value, the second parameter contains the corresponding key. If this function returns true, the key is returned from array_find_key and the callback will not be called for further elements.

The function returns the first array key for which the $callback returns true. If no matching entry is found, the function returns NULL.

$array = [
    'a' => 'dog',
    'b' => 'cat',
    'c' => 'cow',
    'd' => 'duck',
    'e' => 'goose',
    'f' => 'elephant'
];
 
// Find the first animal with a name longer than 4 characters.
var_dump(array_find_key($array, function (string $value) {
    return strlen($value) > 4;
})); // string(1) "e"
 
// Find the first animal whose name begins with f. 
var_dump(array_find_key($array, function (string $value) {
    return str_starts_with($value, 'f'); 
})); // NULL
 
// Find the first animal where the array key is the first symbol of the animal.
var_dump(array_find_key($array, function (string $value, $key) {
   return $value[0] === $key;
})); // string(1) "c"
 
// Find the first animal where the array key matching a RegEx.
var_dump(array_find_key($array, function (string $value, $key) {
   return preg_match('/^([a-f])$/', $key);
})); // string(1) "a"

Functions created by the user and named array_find or array_find_key lead to a PHP error with the new version. A quick GitHub search shows, that there a 656 results defining the symbol array_find for the language PHP. Looking at the search results I estimate about 30% of these results are functions that are not located in a namespace and are not part of a class. array_find_key is defined 28 times on GitHub.

PHP 8.4

None.

None.

None.

None.

None.

None.

This RFC only adds two new functions to PHP and only affects previously defined functions which are named as the proposed functions.

https://github.com/joshuaruesweg/php-src/commit/9f3fc252b92f534d498e5f1e6a463e15f45da208

• [1] GitHub currently has 656 results for array_find and Laravel implements this feature by default with array_first.
• https://en.cppreference.com/w/cpp/algorithm/find
• https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/find
• https://doc.rust-lang.org/std/iter/trait.Iterator.html#method.find