array_find

(PHP 8 >= 8.4.0)

array_find — Returns the first element satisfying a callback function

说明

array_find(array $array, callable $callback): mixed

array_find() returns the value of the first element of an array for which the given callback returns true. If no matching element is found the function returns null.

参数

array

The array that should be searched.

callback

The callback function to call to check each element, which must be

callback(mixed $value, mixed $key): bool

If this function returns true, the value is returned from array_find() and the callback will not be called for further elements.

返回值

The function returns the value of the first element for which the callback returns true. If no matching element is found the function returns null.

示例

示例 #1 array_find() example

<?php
$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;
}));

// Find the first animal whose name begins with f.
var_dump(array_find($array, function (string $value) {
    return str_starts_with($value, 'f');
}));

// 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;
}));

// 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);
}));
?>

以上示例会输出：

string(5) "goose"
NULL
string(3) "cow"
string(3) "dog"

参见

array_find_key() - Returns the key of the first element satisfying a callback function
array_all() - Checks if all array elements satisfy a callback function
array_any() - Checks if at least one array element satisfies a callback function
array_filter() - 使用回调函数过滤数组的元素
array_reduce() - 用回调函数迭代地将数组简化为单一的值

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用户贡献的备注 2 notes

down

mail at nititech dot de ¶

7 months ago

A simple fallback For older PHP versions, that do not have array_find:

<?php

/**
 * Porting of PHP 8.4 function
 *
 * @template TValue of mixed
 * @template TKey of array-key
 *
 * @param array<TKey, TValue> $array
 * @param callable(TValue $value, TKey $key): bool $callback
 * @return ?TValue
 *
 * @see https://www.php.net/manual/en/function.array-find.php
 */
function array_find(array $array, callable $callback): mixed
{
    foreach ($array as $key => $value) {
        if ($callback($value, $key)) {
            return $value;
        }
    }

    return null;
}
?>

down

harl at gmail dot com ¶

21 days ago

Note that if null satisfies the callback then there is no way to tell if null was returned because it was found in the array or if it was because nothing satisfying the callback was found.

In this case, it'll be more robust to use array_find_key; null can't be a key, so if that's what you get it must be because the search failed to find a match.

Obviously, you'd then use the array key to look up the corresponding value in the array.