PHP magic methods: __isset and _ unset

: This article mainly introduces the PHP magic methods __isset and _ unset. if you are interested in the PHP Tutorial, refer to it. In versions later than php5, classes can use magic methods. Php requires that all methods starting with two underscores (_) are retained as magic methods. Therefore, we recommend that you do not use the _ open header for function names unless you want to reload the existing magic methods.

Currently, php's existing magic methods include _ construct ,__ destruct ,__ call ,__ get ,__ set ,__ isset ,__ unset ,__ sleep ,__ wakeup ,__ toString, __set_state and _ clone.

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_ Isset ()-If there is no or non-public attribute when the isset () method is used for attributes in the class or non-class, the _ isset () method is automatically executed.

_ Unset ()-When the unset () method is used for attributes in the class or non-class, if there is no or non-public attribute, the _ unset () method is automatically executed.

 Public = 'pub'; $ this-> protected = 'pro'; $ this-> private = 'pri ';} public function _ isset ($ var) {echo 'here, the attribute name is viewed using the _ isset () method '. $ var. "\ n";} public function _ unset ($ var) {echo 'Here we use the _ unset () method to destroy the attribute name '. $ var. "\ n" ;}}$ exa = new Example; echo'
';var_dump(isset($exa->public));echo "\n";var_dump(isset($exa->protected));echo "\n";var_dump(isset($exa->private));echo "\n";var_dump(isset($exa->noVar));echo "\n";echo '
  ';unset($exa->public);var_dump($exa);echo "\n";unset($exa->protected);echo "\n";unset($exa->private);echo "\n";unset($exa->noVar);echo "\n";
The result is as follows:
Bool (true) Here we use the _ isset () method to view the attribute name protectedbool (false). here we use the _ isset () method to view the attribute name privatebool (false) here, we use the _ isset () method to view the attribute named noVarbool (false) jsonobject (Example) #1 (2) {["protected: protected"] => string (3) "pro" ["private: private"] => string (3) "pri"} Here we use the _ unset () method to destroy the property name protected. here we use _ unset () method to destroy the property name private here the _ unset () method is used to destroy the property name noVar
 
                                                
The above describes the PHP magic methods __isset and _ unset, including the PHP magic methods, and hope to help those who are interested in the PHP Tutorial.