超越PHP - Exceed PHP: array_keys

array_keys

(PHP 4 , PHP 5)

array_keys -- 返回数组中所有的键名

说明

array array_keys ( array input [, mixed search_value])

array_keys() 返回 input 数组中的数字或者字符串的键名。

如果指定了可选参数 search_value，则只返回该值的键名。否则 input 数组中的所有键名都会被返回。

例子 1. array_keys() 例子

<?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)); ?>
以上程序输出为：
Array ( [0] => 0 [1] => color ) Array ( [0] => 0 [1] => 3 [2] => 4 ) Array ( [0] => color [1] => size )

参见 array_values() 和 array_key_exists()。

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array_keys

jacob at keystreams dot com
21-Aug-2002 02:05

Here is a way to use array_intersect on array keys rather than
values:



<?php

$a = array("apple" =>
"red", "banana" => "yellow");

$z =
array("apple" => "green", "peach" =>
"orange", "banana" =>
"rotten");



$intersected_keys =
array_intersect(array_keys($a),
array_keys($z));



print_r($intersected_keys);

?>



This
will print:



Array ( [0] => apple [1] => banana )

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