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.
is_resource
(PHP 4, PHP 5)
is_resource — 変数がリソースかどうかを調べる
説明
bool is_resource ( mixed $var )指定した変数がリソースかどうかを調べます。
パラメータ
- var
評価する変数。
返り値
var が resource の場合に TRUE、 それ以外の場合に FALSE を返します。
例
例 2519. is_resource() の例
<?php
$db_link = @mysql_connect('localhost', 'mysql_user', 'mysql_pass');
if (!is_resource($db_link)) {
die('Can\'t connect : ' . mysql_error());
}
?>
参考
| リソース型のドキュメント |
| get_resource_type() |
is_resource
tacomage at NOSPAM dot devilishly-deviant dot net
07-Aug-2004 10:10
07-Aug-2004 10:10