Detailed explanation of PHP class and object function examples_PHP tutorial

1. interface_exists, class_exists, method_exists and property_exists:

As the name suggests, you can guess some of their functions from the names of the above functions. I think this is why I like this programming language more and more as I learn more about PHP. Their prototype declarations and brief descriptions are given below. For more information, let’s just look at the example code.

bool interface_exists (string $interface_name [, bool $autoload = true ]) determines whether the interface exists. The second parameter indicates whether to execute __autoload when searching.

bool class_exists (string $class_name [, bool $autoload = true ]) determines whether the class exists. The second parameter indicates whether to execute __autoload when searching.

bool method_exists (mixed $object, string $method_name) Determines whether the specified class or object contains the specified member function.

bool property_exists (mixed $class, string $property) Determines whether the specified class or object contains the specified member variable.

//in another_test_class.php

interface AnotherTestInterface {

}

class AnotherTestClass {

public static function printMe() {

print "This is Test2::printSelf.n";

}

public function doSomething() {

print "This is Test2::doSomething.n";

}

public function doSomethingWithArgs($arg1, $arg2) {

print 'This is Test2::doSomethingWithArgs with ($arg1 = '.$arg1.' and $arg2 = '.$arg2.").n";

}

}

//in class_exist_test.php, the classes and interfaces required in the test code below are located in another_test_class.php,

//You can find the pattern from this. The names of classes and interfaces are in camel case, and the words in the file name are separated by underscores.

//There are two __autoload methods given here. Because the first method is more commonly used and convenient, we comment out the second method here. The difference between them can be viewed in the manual.

function __autoload($classname) {

$nomilizedClassname = strtolower(preg_replace('/([A-Z]w*)([A-Z]w*)([A-Z]w*)/','${1}_${2}_${3 }',$classname));

require strtolower($nomilizedClassname).".php";

}

//spl_autoload_register(function($classname) {

// $nomilizedClassname = strtolower(preg_replace('/([A-Z]w*)([A-Z]w*)([A-Z]w*)/','${1}_${2}_$ {3}',$classname));

// require strtolower($nomilizedClassname).".php";

//});

print "The following case is tested before executing autoload.n";

if (!class_exists('AnotherTestClass',false)) {

print "This class doesn't exist if no autoload.n";

}

if (!interface_exists('AnotherTestInterface',false)) {

print "This interface doesn't exist if no autoload.n";

}

print "nThe following case is tested after executing autoload.n";

if (class_exists('AnotherTestClass',true)) {

print "This class exists if autoload is set to true.n";

}

if (interface_exists('AnotherTestInterface',true)) {

print "This interface exists if autoload is set to true.n";

}

The running results are as follows:

bogon:TestPhp$ php class_exist_test.php

The following case is tested before executing autoload.

This class doesn't exist if no autoload.

This interface doesn't exist if no autoload.

The following case is tested after executing autoload.

This class exists if autoload is set to true.

2. get_declared_classes and get_declared_interfaces:

Returns all currently accessible classes and interfaces, including not only custom classes and interfaces, but also PHP built-in classes and interfaces. Their function declaration is very simple, has no parameters and just returns an array. See the following code:

interface AnotherTestInterface {

}

class AnotherTestClass {

public static function printMe() {

print "This is Test2::printSelf.n";

}

}

print_r(get_declared_interfaces());

print_r(get_declared_classes());

Since the output result is too long and these two functions are relatively simple, the output result will not be given below.

3. get_class_methods, get_class_vars and get_object_vars:

These three functions have one thing in common, that is, they can only obtain all member functions, member variables or non-static member variables within the visible scope of the scope. For example, when called inside a class, all member functions or variables meet the conditions, but when called outside the class, only common functions and variables can be returned.

array get_class_methods (mixed $class_name) Gets the accessible member functions in the specified class.

array get_class_vars (string $class_name) Gets the accessible member variables in the specified class.

array get_object_vars (object $object) Gets accessible non-static member variables.

function output_array($functionName, $items) {

print "$functionName.............................n";

foreach ($items as $key => $value) {

print '$key = '.$key. ' => $value = '.$value."n";

}

}

class TestClass {

public $publicVar = 1;

private $privateVar = 2;

static private $staticPrivateVar = "hello";

static public $staticPublicVar;

private function privateFunction() {

}

function publicFunction() {

output_array("get_class_methods",get_class_methods(__CLASS__));

output_array('get_class_vars',get_class_vars(__CLASS__));

output_array('get_object_vars',get_object_vars($this));

}

}

$testObj = new TestClass();

print "The following is output within TestClass.n";

$testObj->publicFunction();

print "nThe following is output out of TestClass.n";

output_array('get_class_methods',get_class_methods('TestClass'));

output_array('get_class_vars',get_class_vars('TestClass'));

output_array('get_object_vars',get_object_vars($testObj));

The running results are as follows:

bogon:TestPhp liulei$ php class_exist_test.php

The following is output within TestClass.

get_class_methods........................

$key = 0 => $value = privateFunction

$key = 1 => $value = publicFunction

get_class_vars.............

$key = publicVar => $value = 1

$key = privateVar => $value = 2

$key = staticPrivateVar => $value = hello

$key = staticPublicVar => $value =

get_object_vars.............

$key = publicVar => $value = 1

$key = privateVar => $value = 2

The following is output out of TestClass.

get_class_methods........................

$key = 0 => $value = publicFunction

get_class_vars.............

$key = publicVar => $value = 1

$key = staticPublicVar => $value =

get_object_vars.............

$key = publicVar => $value = 1

4. get_called_class and get_class:

string get_class ([ object $object = NULL ]) Gets the class name of the parameter object.

string get_called_class (void) The current class name when the static method is called.

class Base {

static public function test() {

var_dump(get_called_class());

}

}

class Derive extends Base {

}

Base::test();

Derive::test();

var_dump(get_class(new Base()));

var_dump(get_class(new Derive()));

The running results are as follows:

bogon:TestPhp$ php another_test_class.php

string(4) "Base"

string(6) "Derive"

string(4) "Base"

string(6) "Derive"

5. get_parent_class, is_a and is_subclass_of:

These three functions are all related to class inheritance, so I grouped them together.

string get_parent_class ([ mixed $object ]) Gets the parent class of the parameter object, and returns false if there is no parent class.

bool is_a (object $object, string $class_name) determines whether the first parameter object is the $class_name class itself or an object of its parent class.

bool is_subclass_of (mixed $object, string $class_name) determines whether the first parameter object is a subclass of $class_name.

class Base {

static public function test() {

var_dump(get_called_class());

}

}

class Derive extends Base {

}

var_dump(get_parent_class(new Derive()));

var_dump(is_a(new Derive(),'Derive'));

var_dump(is_a(new Derive(),'Base'));

var_dump(is_a(new Base(),'Derive'));

var_dump(is_subclass_of(new Derive(),'Derive'));

var_dump(is_subclass_of(new Derive(),'Base'));

The running results are as follows:

bogon:TestPhp$ php another_test_class.php

string(4) "Base"

bool(true)

bool(true)

bool(false)

bool(false)

bool(true)

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