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Last updated: Thu, 21 Aug 2003


A resource is a special variable, holding a reference to an external resource. Resources are created and used by special functions. See the appendix for a listing of all these functions and the corresponding resource types.

Note: The resource type was introduced in PHP 4

Converting to resource

As resource types hold special handlers to opened files, database connections, image canvas areas and the like, you cannot convert any value to a resource.

Freeing resources

Due to the reference-counting system introduced with PHP4's Zend-engine, it is automatically detected when a resource is no longer referred to (just like Java). When this is the case, all resources that were in use for this resource are made free by the garbage collector. For this reason, it is rarely ever necessary to free the memory manually by using some free_result function.

Note: Persistent database links are special, they are not destroyed by the garbage collector. See also the section about persistent connections.

add a note add a note User Contributed Notes
isaac at chexbox dot com
23-Jun-2002 03:37
For the the oblivious: An example of a resource would be a mysql database connection.

$result = mysql_connect("localhost", "username", "pass");
//$result variable is a resource.

print $result;
//will print: Resource ID#1, or something similar
yasuo_ohgaki at hotmail dot com
21-May-2001 04:04
Resource type values are not saved in session variables. (Programmer must re-initialize resource type in session var anyway, because values held by resources are useless connection to connection)

 Last updated: Thu, 21 Aug 2003
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