key
PHP function
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(PHP 4, PHP 5, PHP 7, PHP 8)
Fetch a key from an array
Description
key(array|object $array): int|string|null
key() returns the index element of the current array position.
Parameters
arrayThe array.
Return Values
The key() function simply returns the key of the array element that's currently being pointed to by the internal pointer. It does not move the pointer in any way. If the internal pointer points beyond the end of the elements list or the array is empty, key() returns null.
Changelog
| Version | Description |
|---|
Examples
key() example
php
<?php
$array = array(
'fruit1' => 'apple',
'fruit2' => 'orange',
'fruit3' => 'grape',
'fruit4' => 'apple',
'fruit5' => 'apple');
// this cycle echoes all associative array
// key where value equals "apple"
while ($fruit_name = current($array)) {
if ($fruit_name == 'apple') {
echo key($array), "\n";
}
next($array);
}
?>The above example will output:
output
fruit1
fruit4
fruit5