Function Reference
PHP Manual

Variable Handling Functions


For information on how variables behave, see the Variables entry in the Language Reference section of the manual.


No external libraries are needed to build this extension.


There is no installation needed to use these functions; they are part of the PHP core.

Runtime Configuration

The behaviour of these functions is affected by settings in php.ini.

Variables Configuration Options
Name Default Changeable Changelog
unserialize_callback_func NULL PHP_INI_ALL Available since PHP 4.2.0.
For further details and definitions of the PHP_INI_* constants, see the php.ini directives.

Here's a short explanation of the configuration directives.

unserialize_callback_func string

The unserialize() callback function will called (with the undefined class' name as parameter), if the unserializer finds an undefined class which should be instanciated. A warning appears if the specified function is not defined, or if the function doesn't include/implement the missing class. So only set this entry, if you really want to implement such a callback-function.

See also unserialize().

Resource Types

This extension has no resource types defined.

Predefined Constants

This extension has no constants defined.

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Function Reference
PHP Manual