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array_key_exists (PHP 4 >= 4.1.0, PHP 5) array_key_exists -- 检查给定的键名或索引是否存在于数组中 说明bool array_key_exists ( mixed key, array search)
array_key_exists() 在给定的 key
存在于数组中时返回 TRUE。key
可以是任何能作为数组索引的值。
例子 1. array_key_exists() 例子 |
<?php
$search_array = array("first" => 1, "second" => 4);
if (array_key_exists("first", $search_array)) {
echo "The 'first' element is in the array";
}
?>
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注:
在 PHP 4.0.6 中本函数名为 key_exists()。
参见 isset()，array_keys()
和 in_array()。
 add a note
User Contributed Notes
array_key_exists
jeff at procata dot com
11-Oct-2003 03:55
In PHP 4.1.2, passing a NULL for the first parameter will result in an
error:
Wrong datatype for first argument in call to
array_key_exists
By 4.3.2 this message has been removed.
use
short circuit operators to emulate the more current behavior under older
versions of PHP:
(is_null($key) || !array_key_exists($key, $search))
26-Jul-2003 01:36
For versions before 4.1.0:
function arrayKeyExists($key, $search)
{
return in_array($key, array_keys($search));
}
17-Jan-2002 10:15
You can't use isset() if the associated value is NULL.
You may be
able to use array_key_exists() instead.
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array_intersect
