array_find_key

(PHP 8 >= 8.4.0)

array_find_key — Returns the key of the first element satisfying a callback function

说明

array_find_key() returns the key 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 of the following signature:

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

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

返回值

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

示例

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

string(1) "e"
NULL
string(1) "c"
string(1) "a"

参见

• array_find() - Returns the first element satisfying a callback function
• array_all() - 检查数组所有元素是否都满足回调函数的条件
• 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