Tencent PHP programmer interview questions - summary of 15 magic methods

Function: Automatically load the file of the class when using the class on the current page

*/

function __autoload($className){

$className=strtolower($className);//It is best to add this step, because the class header Capital letters, some systems distinguish the case of file names

require("$className.class.php");//Load class files One.class.php Two.class.php and This file is in the same directory

echo '---------------------------------< br>';//Test as a marker when calling

}

//Neither of the following two classes are defined in this file

$o=new One();//Use One class, initialize it

$t=new Two();//Use Two class, initialize it Initialization

?>

class PcYoYo{

private $url;

$this->url=$url;

}

}

?>

//Initialize a class

class Person{

private $age;

private $sex;

function walk($hour ,$minute){

echo "$hour :$minute We will walk
";

}

}

//Use the magic method __call

/*****

Function: Automatically call when the object calls a function that does not exist in the class to perform some operations

Parameters: $proName Name of the called function$ args parameter array $proName, $args are custom formal parameters that can be changed to suit your own style, but the meaning of these two parameters is fixed

***** /

function __call($proName,$args){

echo "The $proName doesn't exist! the parameters are";

print_r($args);

echo '
';

}

//Instantiate an object

$p=new Person();

$p->walk(5,39);

//Call a method that does not exist in the Person class Method

$p->work();//If the magic method __call is not used, an error occurs in the program and the error message is Fatal error: Call to undefined method Person::work( ) in D:/phpnow/htdocs/holiday/magic__call.php on line 29

//If the magic method __call is used, when the object calls a function that does not exist in the class, __call is Automatically called to perform certain operations.

?>

//Initialize a class

class Computer{

public $cpu='intel';

private $monitor;

private $keyboard ;

//Set the magic method __clone() function

function __clone(){//If you do not set this magic method, the clone will be exactly the same Yes, the __clone function is similar to the constructor of the class and performs some initialization operations

$this->cpu='AMD';//$this refers to the newly created clone object< ;/p>

}

//Set the destructor to compare the difference between = and clone

function __destruct(){

echo '******************************************< ;br>';

}

}// the end of the class

//Instantiate an object< ;/p>

$c1=new Computer();

//Use the reference method to add a reference, because the reference to the object is the stack memory stored in the memory In pointer terms, this means creating a pointer in the memory pointing to the object pointed to by $c1

//We can judge whether this is true by using the destructor Copied the object

$c2=$c1;

//Use the clone method to clone an object

$c3= clone $c1;

//Output the information comparison between the two

echo $c1->cpu,'
';

echo $c3->cpu,'
';

?>

class Person{

private $name;

function __get($para){//There must be a parameter

echo $para.'Does not exist';< /p>

}

}

$p=new Person();

$name =$p->name;//call the __get function

$nation=$p->nation;//never call the __get function

? >

class Pc{

private $key;

echo 'Assign value to '.$key.' .$value.'Failed';

}

}

$p=new Pc();< /p>

$p->key=123;

?>