array_keys
(PHP 4, PHP 5)
array_keys — Return all the keys of an array
說明
array array_keys
( array $input
[, mixed $search_value
[, bool $strict
]] )
array_keys() returns the keys, numeric and string, from the input array.
If the optional search_value is specified, then only the keys for that value are returned. Otherwise, all the keys from the input are returned. As of PHP 5, you can use strict parameter for comparison including type (===).
參數
- input
-
An array containing keys to return.
- search_value
-
If specified, then only keys containing these values are returned.
- strict
-
As of PHP 5, this parameter determines if strict comparision (===) should be used during the search.
Return值
Returns an array of all the keys in input .
範例
Example#1 array_keys() example
<?php
$array = array(0 => 100, "color" => "red");
print_r(array_keys($array));
$array = array("blue", "red", "green", "blue", "blue");
print_r(array_keys($array, "blue"));
$array = array("color" => array("blue", "red", "green"),
"size" => array("small", "medium", "large"));
print_r(array_keys($array));
?>
上例將輸出：
Array ( [0] => 0 [1] => color ) Array ( [0] => 0 [1] => 3 [2] => 4 ) Array ( [0] => color [1] => size )