PHP objects and resources

Object

Object initialization

To initialize an object, use the new statement to instance the object to a variable.

＜?phpclass foo{ function do_foo() { echo "Doing foo."; }}$bar = new foo;$bar->do_foo();?＞

Convert to object

If you convert an object to an object, it will not change. If any other type of value is converted to an object, an instance of the built-in class stdClass will be created. If the value is NULL, the new instance is NULL. For any other value, the member variable named scalar will include this value.

＜?php$obj = (object) 'ciao';echo $obj->scalar; // outputs 'ciao'?＞

Resources

A resource is a special variable that stores a reference to an external resource. Resources are created and used through specialized functions. For all these functions and their corresponding resource types, see the appendix.

Note: The resource type is introduced in PHP 4.

Convert to resource

Resource Type variables are saved as special handles for opening files, database connections, graphic canvas areas, etc. You cannot convert other types of values to resources.

Release resources

Because the PHP4 Zend engine introduces a resource counting system, it can automatically detect that a resource is no longer referenced (the same as Java ). In this case, all external resources used by the resource are released by the garbage collection system. For this reason, some free-result functions are rarely used to manually release the memory.

Note:Persistent database connections are special and will not be damaged by the garbage collection system.