定义和用法
array_search() 函数与 in_array() 一样,在数组中查找一个键值。如果找到了该值,匹配元素的键名会被返回。如果没找到,则返回 false。
在 PHP 4.2.0 之前,函数在失败时返回 null 而不是 false。
如果第三个参数 strict 被指定为 true,则只有在数据类型和值都一致时才返回相应元素的键名。
语法
array_search(value,array,strict)
参数 | 描述 |
---|---|
value | 必需。规定在数组中搜索的值。 |
array | 必需。被搜索的数组。 |
strict |
可选。可能的值:
如果值设置为 true,还将在数组中检查给定值的类型。(参见例子 2) |
Example #1 array_search() 例子
复制代码 代码如下:
$array = array(0 => 'blue', 1 => 'red', 2 => 'green', 3 => 'red');
$key = array_search('green', $array); // $key = 2;
$key = array_search('red', $array); // $key = 1;
?>
Warning
本函数可能返回布尔值 FALSE,但也可能返回一个与 FALSE 等值的非布尔值,例如 0 或者 ""。请参阅布尔类型章节以获取更多信息。应使用 === 运算符来测试本函数的返回值。
例子 1
复制代码 代码如下:
$a=array("a"=>"Dog","b"=>"Cat","c"=>"Horse");
echo array_search("Dog",$a);
?>
输出:a
例子 2
复制代码 代码如下:
$a=array("a"=>"5","b"=>5,"c"=>"5");
echo array_search(5,$a,true);
?>
输出:
b

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Multiple calls to session_start() will result in warning messages and possible data overwrites. 1) PHP will issue a warning, prompting that the session has been started. 2) It may cause unexpected overwriting of session data. 3) Use session_status() to check the session status to avoid repeated calls.

Configuring the session lifecycle in PHP can be achieved by setting session.gc_maxlifetime and session.cookie_lifetime. 1) session.gc_maxlifetime controls the survival time of server-side session data, 2) session.cookie_lifetime controls the life cycle of client cookies. When set to 0, the cookie expires when the browser is closed.


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