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(PHP 4, PHP 5)
is_resource — Prüft, ob eine Variable vom Typ resource ist
Die zu untersuchende Variable.
Gibt TRUE zurück, wenn var vom Typ resource ist, andernfalls FALSE.
Beispiel #1 is_resource()-Beispiel
<?php
$db_link = @mysql_connect('localhost', 'mysql_user', 'mysql_pass');
if (!is_resource($db_link)) {
die('Verbindung konnte nicht hergestellt werden : ' . mysql_error());
}
?>
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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