is_resource

(PHP 4, PHP 5)

is_resource --  Finds whether a variable is a resource

Описание

bool is_resource ( mixed var )

Finds whether the given variable is a resource.

Список параметров

var

The variable being evaluated.

Возвращаемые значения

Returns TRUE if var is a resource, FALSE otherwise.

Примеры

Пример 1. is_resource() example

<?php

$db_link
= @mysql_connect('localhost', 'mysql_user', 'mysql_pass');
if (!
is_resource($db_link)) {
   die(
'Can\'t connect : ' . mysql_error());
}

?>



is_resource
tacomage at NOSPAM dot devilishly-deviant dot net
06-Aug-2004 06:10
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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 Last updated: Tue, 15 Nov 2005