array_find_key
PHP function
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(PHP 8 >= 8.4.0)
Returns the key of the first element satisfying a callback function
Description
array_find_key(array $array, callable $callback): mixed
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.
Parameters
arrayThe Array that should be searched.
callbackThe callback function to call to check each element, which must be of the following signature:
callback(mixed $value, mixed $key): boolIf this function returns true, the key is returned from
array_find_key()and the callback will not be called for further elements.
Return Values
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.
Examples
array_find_key() example
php
<?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);
}));
?>The above example will output:
output
string(1) "e"
NULL
string(1) "c"
string(1) "a"