is_resource

描述

bool is_resource ( mixed var )

如果给出的参数 var 是 resource 类型，is_resource() 返回 TRUE，否则返回 FALSE。

查看 resource 类型文档获取更多的信息。

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tacomage at NOSPAM dot devilishly-deviant dot net
07-Aug-2004 09:10


Note that the use of is_resource isn't necessary in the example.  mysql_connect (along with any other function that would return a resouce, I imagine) returns false on failure, so the same results could be obtained with:

<?php



$db_link = @mysql_connect('localhost', 'mysql_user', 'mysql_pass');

if (!$db_link) {

   die('Can\'t connect : ' . mysql_error());

}



?> 



Or even:

<?php

  $db_link = @mysql_connect('localhost', 'mysql_user', 'mysql_pass')

  or die('Can\'t connect : ' . mysql_error());

}

?>



You'd be more likely to use is_resource AFTER the initial conection, to make sure the variable you intend to use as a resource is, in fact, a connection resource.  You might also use is_resource as a sanity-check prior to serializing an object, since resource variables can't be serialized.

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