<?php

echo "Hello world";

// 脚本至此结束，并无PHP 结束标记

<p>这里是 HTML 文件内容不会被解析</p>
<?php echo '这里的内容会被解析'; ?>
<p>这里的内容也不会被解析</p>

<?php
    echo "This is a test";
?>

<?php echo "this is a test" ?>

<?php echo "We omitted the last closing tag";

<?php
echo "First line";
echo "Last line"

<?php
echo "First line";
echo "Last line";

<?php
echo "First line";
echo "Last line" ?>

<?php

echo "This is a test"; // This is a one-line c++ style comment

/**
 * This is a multi line comment
 * yet another line of comment
 */

echo "This is yet another test";
echo "One Final Test"; # This is a one-line shell-style comment

<?php
// 下面这一句在 PHP5.4.16运行正常
// php 7.0.x PHP Parse error:  Invalid numeric literal
var_dump(01090); // 八进制010 = 十进制 8

<?php
// $a 和 $b 在小数点后五位精度内都是相等的
$a = 1.23456789;
$b = 1.23456780;
$epsilon = 0.00001;

if(abs($a-$b) < $epsilon) {
    echo "true";
}

<?php
# 1 非法的示例
class foo {
    public $bar = <<<EOT
bar
    EOT;
}
?>

# 2 正确的示例
$str = <<<EOD
Example of string spanning multiple lines
useing heredoc syntax.
EOD;

/*含有变量的更复杂的示例*/
class foo
{
    var $foo;
    var $bar;
    
    function foo()
    {
        $this->foo = 'Foo';
        $this->bar = array('Bar1', 'Bar2', 'Bar3');
    }
}

$foo = new foo();
$name = 'MyName';

echo <<<EOT
My name is "$name". I am printing some $foo->foo.
Now, I am printing some {$foo->bar[1]}.
This should print a capital 'A': \x41
EOT;
// 输出结果如下
My name is "MyName". I am printing some Foo.
Now, I am printing some Bar2.
This should print a capital 'A': A

<?php
// 静态变量
function foo() {
    static $bar = <<<LABEL
Nothing in here...
LABEL;
}

// 类的常量，属性
class foo {
    const BAR = <<<FOOBAR
Constant example
FOOBAR;

    public $baz = <<<"FOOBAR"
property example
FOOBAR;
}

<?php
$str = <<<'EOD'
Example of string useing nowdoc syntax.
EOD;

class foo
{
    var $foo;
    var $bar;
    
    function foo()
    {
        $this->foo = 'Foo';
        $this->bar = array('Bar1', 'Bar2', 'Bar3');
    }
}

$foo = new foo();
$name = 'MyName';

echo <<<'EOT'
My name is "$name". I am printing some $foo->foo.
Now, I am printing some {$foo->bar[1]}.
This should print a capital 'A': \x41
EOT;
// 内用将原样输出不做解析

<?php

# 数组间接引用
function getArray() {
    return array(1, 2, 3);
}

// on PHP 5.4
$secondElement = getArray()[1];

// previously
$tmp = getArray();
$secondElement = $tmp[1];

// or
list(, $secondElement) = getArray();

<?php
$arr = [5=>1, 12=>2];
$arr[] = 56; // This is the same as $arr[13] = 56 at this point of the script
$arr["x"] = 42; // This adds a new element to the array with key "x"
unset($arr[5]); // This removes the element form the array
unset($arr); // This deletes the whole array

<?php
$a = [1=>'one', 2=>'two', 3=>'three'];
unset($a[2]);
// 现在$a = [1 => 'one', 3=>'three'] 
$b = array_values($a);
// Now $b is [0=>'one', 1=>'three']

<?php
class foo {
    function do_foo() {
        echo "Doing foo.";
    }
}

$bar = new foo;
$bar->do_foo();

# 转换为对象
$obj = (object)'ciao';
echo $obj->scalar; // outputs 'ciao'

// In PHP 7 there are a few ways to create an empty object:
$obj1 = new \stdCalss; // Instantiate stdClass object
$obj2 = new class{}; // Instantiate anonymous class
$obj3 = (object)[];  // Cast empty array to object

var_dump($obj1); // object(stdClass)#1 (0) {}
var_dump($obj2); // object(class@anonymous)#2 (0) {}
var_dump($obj2); // object(stdClass)#1 (0) {}

// $obj1 and $obj3 are the same type, but $obj1 !== $obj3. Also, all three will json_encode() to a simple JS object {}:

echo json_encode([
    new \stdClass,
    new class{},
    (object)[],
]);
// Output: [{},{},{}]

<?php

$c = mysql_connect();
echo get_resource_type($c); // mysql link

$fp = fopen("foo", "w");
echo get_resource_type($fp); // file

<?php

function my_callback_function() {
    echo "hello world";
}

// An example callback method
class MyClass {
    static function myCallbackMethod() {
        echo "Hello World!";
    }
}

// Type1 : Simple callback
call_user_func('my_callback_function');

// Type2 : Static class method call
call_user_func(['MyClass', 'myCallbackMethod']);

// Type3 : Object method call
$obj = new MyClass();
call_user_func([$obj, 'myCallbackMethod']);

// Type4 : Static calss method call (As of PHP 5.2.3)
call_user_func('MyClass::myCallbackMethod');

// Type5 : Relative static calss method call(As of PHP 5.3.0)
class A {
    public static function who() {
        echo "A\n";
    }
}

class B extends A {
    public static function who() {
        echo "B\n";
    }
}

call_user_func(['B', 'parent::who']); // A

// Type6 : Objects implementing __invoke can be used as callables (since PHP 5.3)
class C {
    public function __invoke($name) {
        echo "Hello ", $name, "\n";
    }
}

$c = new C();
call_user_func($c, 'PHP!'); // Hello PHP!

<?php

$double = function($a) {
    return $a * 2;
};

$numbers = range(1, 5);

$new_numbers = array_map($double, $numbers);
print implode(' ', $new_numbers); // 2 4 6 8 10

<?php
// filename: b.php
$a = "demo";
?>

<?php
include "b.php";
echo $a; // demo

<?php
# 全局变量
$a = 1;
$b = 2;

function Sum() {
    $GLOBALS['b'] = $GLOBALS['a'] + $GLOBALS['b']; // 等同于下面两行
    // global $a, $b;
    // $b = $a + $b;
}

Sum();
echo $b; // 3

# 静态变量
function foo() {
    static $int = 0;
    static $int2 = 1 + 2; // wrong
    static $int3 = sqrt(121); // wrong
}

<?php
if (isset($_POST['action']) && $_POST['action'] == 'submitted') {
    echo '<pre>';

    print_r($_POST);
    echo '<a href="'. $_SERVER['PHP_SELF'] .'">Please try again</a>';

    echo '</pre>';
} else {
?>
<form action="<?php echo $_SERVER['PHP_SELF']; ?>" method="post">
    Name:  <input type="text" name="personal[name]"><br />
    Email: <input type="text" name="personal[email]"><br />
    Test1: <input type="text" name="a b"><br />
    Test2: <input type="text" name="c.d"><br />
    Beer: <br>
    <select multiple name="beer[]">
        <option value="warthog">Warthog</option>
        <option value="guinness">Guinness</option>
        <option value="stuttgarter">Stuttgarter Schwabenbr</option>
    </select><br />
    <input type="hidden" name="action" value="submitted" />
    <input type="submit" name="submit" value="submit me!" />
</form>
<?php
}
?>
/*
Array
(
    [personal] => Array
        (
            [name] => pemako
            [email] => pemako@126.com
        )

    [a_b] => a b
    [c_d] => c.d
    [beer] => Array
        (
            [0] => guinness
            [1] => stuttgarter
        )

    [action] => submitted
    [submit] => submit me!
)
*/

<?php

define("CONSTANT1", "Hello world."); // 5.3 之前只能用 define 函数

// Works as of PHP 5.3.0
const CONSTANT = 'Hello World';

echo CONSTANT;

// Works as of PHP 5.6.0
const ANOTHER_CONST = CONSTANT.'; Goodbye World';
echo ANOTHER_CONST;

const ANIMALS = array('dog', 'cat', 'bird');
echo ANIMALS[1]; // outputs "cat"

// Works as of PHP 7
define('ANIMALS', array(
    'dog',
    'cat',
    'bird'
));
echo ANIMALS[1]; // outputs "cat"

<?php
echo (5 % 3)."\n";           // prints 2
echo (5 % -3)."\n";          // prints 2
echo (-5 % 3)."\n";          // prints -2
echo (-5 % -3)."\n";         // prints -2

<?php
$a = 3;
$b = &$a; // $b 是 $a 的引用

print "$a\n"; // 输出 3
print "$b\n"; // 输出 3

$a = 4; // 修改 $a

print "$a\n"; // 输出 4
print "$b\n"; // 也输出 4，因为 $b 是 $a 的引用，因此也被改变

<?php
$output = `ls -al`;
echo "<pre>$output</pre>";

<?php
$a = array("a" => "apple", "b" => "banana");
$b = array("a" => "pear", "b" => "strawberry", "c" => "cherry");

$c = $a + $b; // Union of $a and $b
echo "Union of \$a and \$b: \n";
var_dump($c);

$c = $b + $a; // Union of $b and $a
echo "Union of \$b and \$a: \n";
var_dump($c);

$a += $b; // Union of $a += $b is $a and $b
echo "Union of \$a += \$b: \n";
var_dump($a);

$a = array("apple", "banana");
$b = array(1 => "banana", "0" => "apple");

var_dump($a == $b); // bool(true)
var_dump($a === $b); // bool(false)

/* output
Union of $a and $b:
array(3) {
  ["a"]=>
  string(5) "apple"
  ["b"]=>
  string(6) "banana"
  ["c"]=>
  string(6) "cherry"
}
Union of $b and $a:
array(3) {
  ["a"]=>
  string(4) "pear"
  ["b"]=>
  string(10) "strawberry"
  ["c"]=>
  string(6) "cherry"
}
Union of $a += $b:
array(3) {
  'a' =>
  string(5) "apple"
  'b' =>
  string(6) "banana"
  'c' =>
  string(6) "cherry"
}
*/

<?php
# 1 对类使用 instanceof
class MyClass{}
class NotMyClass{}
$a = new MyClass;
var_dump($a instanceof MyClass); // bool(true)
var_dump($a instanceof NotMyClass); // bool(false)
?>

<?php
# 2 对继承类的使用
class ParentClass {}
class MyClass extends ParentClass {}
$a = new MyClass;
var_dump($a instanceof MyClass);	// bool(true)
var_dump($a instanceof ParentClass);// bool(true)
?>

<?php
# 3 使用 instanceof 检查对象不是某个类的实例
class MyClass {}
$a = new MyClass;
var_dump(!($a instanceof stdClass)); // bool(true)
?>

<?php
# 4 对接口使用 instanceof
interface MyInterface {}
class MyClass implements MyInterface {}
$a = new MyClass;
var_dump($a instanceof MyClass);	// bool(true)
var_dump($a instanceof MyInterface);// bool(true)
?>

<?php
# 5 对其他变量使用 instanceof
interface MyInterface {}
class MyClass implements MyInterface {}
$a = new MyClass;
$b = new MyClass;
$c = 'MyClass';
$d = 'NotMyClass';

var_dump($a instanceof $b);	//$b is an object of class MyClass bool(true)
var_dump($a instanceof $c); //$c is a string 'MyClass'  bool(true)
var_dump($a instanceof $d); //$d is a string 'NotMyClass' bool(false)
?>

<?php
# 6 用 instanceof 检测其它变量
$a = 1;
$b = NULL;
$c = imagecreate(5, 5);
var_dump($a instanceof stdClass); // $a is an integer bool(false)
var_dump($b instanceof stdClass); // $b is NULL bool(false)
var_dump($c instanceof stdClass); // $c is a resource bool(false)
var_dump(FALSE instanceof stdClass); //PHP Fatal error:  instanceof expects an object instance, constant given

<?php
# 1. Tick 的用法示例

declare(ticks=1); // 如果有 register_tick_function() 表明每执行一行代码调用一次注册的函数

// A function called on each tick event
function tick_handler() {
	static $num = 0;
	$num++;
	echo "tick_handle() called $num times.\n";
}

register_tick_function('tick_handler');

$a = 1;

if($a > 0) {
	$a += 2;
	echo "$a \n";
}

/* output
tick_handler() called 1 times.
tick_handler() called 2 times.
tick_handler() called 3 times.
3
tick_handler() called 4 times.
*/
?>

<?php
# 2. Ticks 的用法 上面的代码执行顺序和下面相同
// A function called on each tick event
function tick_handler() {
	static $num = 0;
	$num++;
	echo "tick_handle() called $num times \n";
}

$a = 1;
tick_handler();

if($a > 0) {
	$a += 2;
	tick_handler();
	echo "$a \n";
	tick_handler();
}
tick_handler();
?>

<?php
# 3. Tick 调用类中的方法
declare(ticks=1);

// using a function as the callback
register_tick_function('my_function', true);

// using an object->method
$obj = new MyClass;
register_tick_function([&obj, 'my_method'], true);
?>

<?php
# FileName: signal.php
declare(ticks=1);
pcntl_signal(SIGINT, function(){
	exit("Get signal SIGINT and exit\n);
});

echo "Ctl + c or run cmd : kill -SIGINT " . posix_getpid(). "\n" ;

while(true) {
	$a++;
}
/*
while output:
Ctl + c or run cmd : kill -SIGINT 62062
^CGet signal SIGINT and exit 
*/

<?php
# 2. 使用 encoding指令来对每段脚本指定其编码方式
declare(encodng='IOS-8859-1');
// code here
// 当和命名空间结合起来时 declare 的唯一合法语法是 declare(encoding='...');
// 其中 ... 是编码的值。而 declare(encoding='...') {} 将在与命名空间结合时产生解析错误

<?php
# 3. 使用strict_types 声明严格模式 类似于js 的 strict mode
declare(strict_types=1);

function foo(int $a): int {
	return $a * 2;
}

// 上面代码表示 foo 函数的参数和返回值必须是整数 如果不是整数的话会抛出错误
foo(1.0)
// PHP Fatal error:  Uncaught TypeError: Argument 1 passed to foo() must be of the type integer, float given

<?php
function sum(...$numbers) {
	$acc = 0;
	foreach($numbers as $n) {
		$acc += $n;
	}
	return $acc;
}

echo sum(1, 2, 3, 4); // 10

function add($a, $b) {
	return $a + $b;
}

echo add(...[1, 2])."\n"; // 3

$a = [1, 2];
echo add(...$a); // 3
?>

<?php

// Older version of PHP
function sum() {
	$acc = 0;
	foreach(func_get_args() as $n) {
		$acc += $n;
	}
	return $acc;
}
echo sum(1, 2, 3, 4); // 10

<?php
echo preg_replace_callback('/-([a-z])/', function ($match) {
    return strtoupper($match[1]);
}, 'hello-world');
// 输出 helloWorld

<?php
#1 简单的类定义
class SimpleClass {
    // property declaration
    public $var = 'a default value';

    // method declaration
    public function displayVar() {
        echo $this->var;
    }
}

// 当一个方法在类定义内部被调用时，有一个可用的伪变量$this。$this 是一个到主叫对象的引用
// (通常是该方法所从属的对象，但如果是从第二个对象静态调用时也可能是另一个对象)

#2 $this 伪变量的示例

class A {
    function foo() {
        if(isset($this)) {
            echo '$this is defind ('. get_class($this). ")\n";
        } else {
            echo "\$this is not defined.\n";
        }
    }
}

class B {
	function bar() {
		A::foo(); // Note: the next line will issue a warning if E_STRICT is enabled.
	}
}

$a = new A();
$a->foo(); // $this is defined (A)

A::foo();

$b = new B();
$b->bar();

B::bar();

/*
# PHP5 output 
$this is defined (A)
$this is not defined.
$this is defined (B)
$this is not defined.

# PHP7 output
$this is defined (A)
$this is not defined.
$this is not defined.
$this is not defined.
*/

<?php

# 创建一个实例
$instance = new SimpleClass();

// 也可以如下面这样
$className = 'SimpleClass';
$instance = new $className();

<?php
class MyClass {
    const CONSTANT = 'constant test';

    function showConstant() {
        echo self::CONSTANT ."\n";
    }
}

echo MyClass::CONSTANT;

$obj = new MyClass;
$obj->showConstant();

$obj::CONSTANT; // PHP5.3.0

<?php
function __autoload($class_name) {
    require_once $class_name . '.php';
}

$obj  = new MyClass1(); // 会自定调用 __autoload() 函数并试图在当前文件夹下加载 MyClass1.php 文件
                        // 如果不存在也会抛出一个致命错误
$obj2 = new MyClass2();
?>

<?php
// 假定当前目录下只要 MyClass1.php 没有 MyClass2.php
<?php

spl_autoload_register(function ($name) {
    if(file_exists("$name.php")) {
        require_once("$name.php");
    } else {
        throw new Exception("Unable load $name.php");
    }
});

try {
    $obj = new Class1();
    $obj2 = new Class2();
}catch(Exception $e) {
    echo $e->getMessage()."\n"
} 

// Unable load Class2.php

<?php
abstract class AbstractClass
{
 // 强制要求子类定义这些方法
    abstract protected function getValue();
    abstract protected function prefixValue($prefix);

    // 普通方法（非抽象方法）
    public function printOut() {
        print $this->getValue() . "\n";
    }
}

class ConcreteClass1 extends AbstractClass
{
    protected function getValue() {
        return "ConcreteClass1";
    }

    public function prefixValue($prefix) {
        return "{$prefix}ConcreteClass1";
    }
}

class ConcreteClass2 extends AbstractClass
{
    public function getValue() {
        return "ConcreteClass2";
    }

    public function prefixValue($prefix) {
        return "{$prefix}ConcreteClass2";
    }
}

$class1 = new ConcreteClass1;
$class1->printOut();
echo $class1->prefixValue('FOO_') ."\n";

$class2 = new ConcreteClass2;
$class2->printOut();
echo $class2->prefixValue('FOO_') ."\n";

/*
ConcreteClass1
FOO_ConcreteClass1
ConcreteClass2
FOO_ConcreteClass2
*/

<?php

// Declare the interface 'iTemplate'
interface iTemplate {
    public function setVariable($name, $var);
    public function getHtml($template);
}

// Implement the interface
// This will work

class Template implements iTemplate {
    private $vars = [];

    public function setVariable($name, $var) {
        $this->vars[$name] = $var;
    }

    public function getHtml($template) {
        foreach($this->vars as $name => $value) {
            $template = str_replace('{'. $name . '}', $value, $template);
            echo $template;
        }

        return $template;
    }
}


// Extendable Interfaces
interface a {
    public function foo();
}

interface b {
    public function baz(Baz $baz);
}

// This will work
class c implements b {
    // 实现 a b 两个接口的方法
    public function foo() {
    }

    public function baz(Baz $baz) {
    }
}


// Multiple interface inheritance
interface m {
    public function foo();
}

interface n {
    public function bar();
}

interface o extends m, n {
    public function baz();
}

class p implements o {
    public function foo(){}

    public function bar(){}

    public function baz(){}
}

// Interfaces with constants
interface q {
    const b = 'Interface constant';
}

//Prints: Interface constant
echo q::b;

// This will however not work because it's not allowed to override constants.
class b implements a {
    const b = 'Class constant';
}

<?php
trait HelloWorld {
    public function sayHello() {
        echo 'Hello World!';
    }
}

class TheWorldIsNotEnough {
    use HelloWorld;
    public function sayHello() {
        echo 'Hello Universe!';
    }
}

$o = new TheWorldIsNotEnough();
$o->sayHello();  // Hello Universe

<?php
trait Hello {
    public function sayHello() {
        echo 'Hello ';
    }
}

trait World {
    public function sayWorld() {
        echo 'World';
    }
}

class MyHelloWorld {
    use Hello, World;
    public function sayExcalamtionMark() {
        echo "!";
    }
}

$o = new MyHelloWorld();
$o->sayHello();
$o->sayWorld();
$o->sayExcalamtionMark();

<?php

# 解决两个 trait 都拥有同一个方法的冲突

trait A {
    public function smallTalk() {
        echo 'a';
    }

    public function bigTalk() {
        echo 'A';
    }
}

trait B {
    public function smallTalk() {
        echo 'b';
    }

    public function bigTalk() {
        echo 'B';
    }
}

class Talker {
    use A, B {
        // 表示用 B中的 smallTalk 替代 A 中的 samllTalk
        B::smallTalk insteadof A;
        // 表示用 A中的 bigTalk 替代 B 中的 bigTalk
        A::bigTalk insteadof B;
    }
}

$o = new Talker();
$o->smallTalk(); //b
$o->bigTalk();  // A

class Aliased_Talker {
    use A, B {
        B::smallTalk insteadof A;
        A::bigTalk insteadof B;
        B::bigTalk as talk;
    }
}

$o = new Aliased_Talker();
$o->smallTalk(); // b
$o->bigTalk();  // A
$o->talk(); // B

<?php
trait HelloWorld {
    public function sayHello() {
        echo 'Hello World!';
    }
}

// 修改 sayHello 的访问控制
class MyClass1 {
    use HelloWorld { sayHello as protected; }
}

// 给方法一个改变了访问控制的别名
// 原来的 sayHello 的访问控制则没有发生改变

class MyClass2 {
    use HelloWorld { sayHello as private myPrivateHello; }
}

$o1 = new MyClass1();
$o1->sayHello(); // 报错访问一个受保护的方法

$o2 = new MyClass2();
$o2->sayHello();    // Hello World!

$o2->myPrivateHello(); // 报错访问一个私有的方法

<?php
trait Hello {
    public function sayHello() {
        echo 'Hello';
    }
}

trait World {
    public function sayWorld() {
        echo 'World';
    }
}

trait HelloWorld {
    use Hello, World;
}

class MyHelloWorld {
    use HelloWorld;
}

$o = new MyHelloWorld();
$o->sayHello(); // Hello 
$o->sayWorld(); // World

<?php
trait Hello {
    public function sayHelloWorld() {
        echo 'Hello '.$this->getWorld();
    }
    abstract public function getWorld();
}

class MyHelloWorld {
    private $world;
    use Hello;
    public function getWorld() {
        return $this->world;
    }

    public function setWorld($val) {
        $this->world = $val;
    }
}

$o = new MyHelloWorld();
$o->setWorld('demo');
echo $o->getWorld();

<?php
trait Counter {

	public $x = 1;

    public function inc() {
        static $c = 0;
        $c = $c + 1;
        echo "$c \n";
    }

	public static function doSomething() {
		return "Doing something\n";
	}
}

class C1 {
    use Counter;
}

class C2 {
    use Counter;
}

$o = new C1();
$o->inc(); // 1
$o->inc(); // 2

echo Counter::doSomething();

echo $o->x; // 1

$p = new C2();
$p->inc(); // 1
$p->inc(); // 2

<?php
trait PropertiesTrait {
    public $same = true;
    public $different = false;
}

class PropertiesExample {
    use PropertiesTrait;
    public $same = true; // Strict Standards
    public $different = true; // 致命错误
}

<?php
// PHP 7 之前的代码

class Logger
{
    public function log($msg) {
        echo $msg;
    }
}


$obj = new Logger();
$obj->log('This is demo!');


//  PHP7+
$obj2 = (new class {
    public function log($msg) {
        echo $msg;
    }
});

$obj2->log('这个是匿名类');
?>

<?php

class SomeClass{}
interface SomeInterface {}
trait SomeTrait {}

var_dump(new class(10) extends SomeClass implements SomeInterface {
    private $num;

    public function __construct($num) {
        $this->num = $num;
    }

    use SomeTrait;
});

//object(class@anonymous)#1 (1) {
//  ["num":"class@anonymous":private]=>
//  int(10)
//}

<?php

class Outer {
    private $prop = 1;
    protected $prop2 = 2;

    protected function func1() {
        return 3;
    }

    public function func2() {
        return new class($this->prop) extends Outer {
            private $prop3;

            public function __construct($prop) {
                $this->prop3 = $prop;
            }

            public function func3() {
                return $this->prop2 + $this->prop3 + $this->func1();
            }
        };
    }
}

echo (new Outer)->func2()->func3(); // 6

<?php

class PropertyTest {
    // 被重载的数据保存在此
    private $data = [];

    // 重载不能被用在已经定义的属性
    public $declared = 1;

    // 只有从外部访问这个属性时，重载才会发生
    private $hidden = 2;

    public function __set($name, $value) {
        echo "Setting '$name' to '$value' \n";
        $this->data[$name] = $value;
    }

    public function __get($name) {
        echo "Getting '$name' \n";
        if(array_key_exists($name, $this->data)) {
            return $this->data[$name];
        }

        $trace = debug_backtrace();
        trigger_error(
            'Undefined property via __get(): '. $name .
            ' in '. $trace[0]['file'] .
            ' on line '. $trace[0]['line'],
            E_USER_NOTICE);

        return null;
    }

    // PHP 5.1.0 之后版本
    public function __isset($name) {
        echo "Is '$name' set?\n";
        return isset($this->data[$name]);
    }

    public function __unset($name) {
        echo "Unsetting '$name' \n";
        unset($this->data[$name]);
    }

    public function getHidden()
    {
        return $this->hidden;
    }
}

echo "<pre>\n";

$obj = new PropertyTest;

$obj->a = 1;
echo $obj->a . "\n\n";

var_dump(isset($obj->a)); // bool(true)
unset($obj->a); // 
var_dump(isset($obj->a)); // bool(false)

echo $obj->declared . "\n\n";

// 私有属性的访问
echo $obj->getHidden() . "\n\n";

echo $obj->hidden; // Will call__get() 函数

<?php

class MethodTest {
    public function __call($name, $arguments) {
        echo "Calling object method '$name' "
            . implode(',', $arguments). "\n";
    }

    // PHP 5.3.0+
    public static function __callStatic($name, $arguments) {
        echo "Calling object method '$name' "
            . implode(',', $arguments). "\n";
    }
}


$obj = new MethodTest;
$obj->runTest('in object context'); // Calling object method 'runTest' in object context

// Calling object method 'runTest' in static context
MethodTest::runTest('in static context'); // PHP5.3.0+

// IteratorAggregate 只需要实现getIterator 方法即可
<?php
class myData implements IteratorAggregate {
    protected $property = 'Protected property';
    public $property1 = 'Public property one';
    public $property2 = 'Public property two';
    public $property3 = 'Public property three';

    public function __construct() {
        $this->property4 = "last property";
    }

    public function getIterator() {
        return new ArrayIterator($this);
    }
}

$obj = new myData;

foreach($obj as $key=>$value) {
    echo "$key=>$value\n";
}
/*
property1=>Public property one
property2=>Public property two
property3=>Public property three
property4=>last property
*/

<?php
class Person {

    private $name, $age, $sex, $info;

    public function __construct($name, $age, $sex) {
        $this->name = $name;
        $this->age = $age;
        $this->sex = $sex;
        $this->info = sprintf("prepared by construct magic function name: %s, age: %d sex: %s",
        $this->name, $this->age, $this->sex);
    }

    public function getInfo() {
        echo $this->info . PHP_EOL;
    }

    // serialize 前调用 用于删除需要被序列化存储的成员变量
    // return array
    public function __sleep(){
        echo __METHOD__. PHP_EOL;
        // 序列化只会存储 name, age, sex , info 不会被序列化
        return ['name', 'age', 'sex'];
    }

    // unserialize 钱调用，用于预先准备对象资源
    public function __wakeup() {
        echo __METHOD__ .PHP_EOL;
        $this->info = sprintf("prepared by wakeup magic function name: %s age: %d sex: %s", 
                                $this->name, $this->age, $this->sex);
    }
}

$man = new Person('pemako', 26, 'man');
$man->getInfo();

$temp = serialize($man);
echo $temp. PHP_EOL;

// 反序列化先调用 __wakeup
$man = unserialize($temp);
$man->getInfo();

/*
prepared by construct magic function name: pemako, age: 26 sex: man
Person::__sleep
O:6:"Person":3:{s:12:"Personname";s:6:"pemako";s:11:"Personage";i:26;s:11:"Personsex";s:3:"man";}
Person::__wakeup
prepared by wakeup magic function name: pemako age: 26 sex: man
*/

<?php

class CallableClass {
    function __invoke($x) {
        var_dump($x);
    }
}

$obj = new CallableClass;
$obj(5); // int(5)
var_dump(is_callable($obj));// bool(true)

# var_export() 函数
$a = [1, 2, ["a", "b", "c"]]
var_export($a);
/*
array (
  0 => 1,
  1 => 2,
  2 =>
  array (
    0 => 'a',
    1 => 'b',
    2 => 'c',
  ),
)
*/

class A {
    public $var1;
    public $var2;

    public static function __set_state($array) {
        $obj = new A;
        $obj->var1 = $array['var1'];
        $obj->var2 = $array['var2'];
        return $obj;
    }
}

$o = new A;
$o->var1 = 5;
$o->var2 = 'foo';

eval('$b ='. var_export($o, true). ';');
var_dump($b);
/*
string(60) "A::__set_state(array(
   'var1' => 5,
   'var2' => 'foo',
))"
*/

$b = var_export($o, true);
var_dump($b);
/*
string(60) "A::__set_state(array(
   'var1' => 5,
   'var2' => 'foo',
))"
*/

<?php

class SubObject {
    static $instances = 0;
    public $instance;

    public function __construct() {
        $this->instance = ++self::$instances;
    }

    public function __clone() {
        $this->instance = ++self::$instances;
    }
}

class MyCloneable {
    public $object1;
    public $object2;

    function __clone() {
        // 强制复制一份this->object， 否则仍然指向同一个对象
        $this->object1 = clone $this->object1;
    }
}

$obj = new MyCloneable();

$obj->object1 = new SubObject();
$obj->object2 = new SubObject();

$obj2 = clone $obj;


print("Original Object:\n");
print_r($obj);

print("Cloned Object:\n");
print_r($obj2);

/*
Original Object:
MyCloneable Object
(
    [object1] => SubObject Object
        (
            [instance] => 1
        )

    [object2] => SubObject Object
        (
            [instance] => 2
        )

)
Cloned Object:
MyCloneable Object
(
    [object1] => SubObject Object
        (
            [instance] => 3
        )

    [object2] => SubObject Object
        (
            [instance] => 2
        )
)
*/

<?php

class C {
    private $prop;

    public function __construct($val) {
        $this->prop = $val;
    }

    public function __debugInfo() {
        return [
            'propSquared' => $this->prop ** 2,
        ];
    }
}

var_dump(new C(42));

/*
 object(C)#1 (1) {
  ["propSquared"]=>
  int(1764)
}
 */

<?php

class A {
    public static function who() {
        echo __CLASS__;
    }

    public static function test() {
        self::who();
        //static::who(); // 延迟静态绑定
    }
}

class B extends A {
    public static function who() {
        echo __CLASS__;
    }
}

B::test(); // A 
// 如果想得到结果为 B 只需注释 self::who() ，打开 static::who()注释即可。则 B::test() 结果为 B

<?php
class A {
    public $foo = 1;
}

$a = new A;
$b = $a; // $a , $b 都是同一个标识符的拷贝  ($a) = ($b) = <id>

$b->foo = 2;

echo $a->foo. "\n"; // 2

$c = new A;
$d = &$c; // $c, $d 是引用 ($c, $d) = <id>

$d->foo = 2;
echo $c->foo."\n"; // 2

$e = new A;
function foo($obj) {
    // ($obj) = ($e) = <id>
    $obj->foo = 2; // 2
}

foo($e);
echo $e->foo. "\n"; // 2

<?php
// classa.inc:
  
class A {
	public $one = 1;

	public function show_one() {
		echo $this->one;
	}
}

// page1.php:

include("classa.inc");

$a = new A;
$s = serialize($a);
// 把变量$s保存起来以便文件page2.php能够读到
file_put_contents('store', $s);

// page2.php:

// 要正确了解序列化，必须包含下面一个文件
include("classa.inc");

$s = file_get_contents('store');
$a = unserialize($s);

// 现在可以使用对象$a里面的函数 show_one()
$a->show_one();

<?php
namespace MyProject;

class CONNECT_OK = 1;
class Connection{}
function connect() {}

<?php
namespace MyProject;

<?php
namespace MyProject\Sub\Level;

<?php
#fil1.php
namespace Foo\Bar\subnamespace;

const FOO = 1;
function foo() {
    echo __NAMESPACE__.PHP_EOL;
}
class foo {
    static function staticmethod() {
        echo __NAMESPACE__.PHP_EOL;
    }
}

<?php

namespace Foo\Bar;
include "file1.php";

const FOO = 2;
function foo() {
    echo __NAMESPACE__.PHP_EOL;
}
class foo {
    public static function staticfunction() {
        echo __NAMESPACE__.PHP_EOL;
    }
}

// 非限定名称
foo();
foo::staticfunction(); 
echo FOO.PHP_EOL;

// 限定名称
subnamespace\foo();
subnamespace\foo::staticmethod();
echo subnamespace\FOO . PHP_EOL;

// 完全限定名
\FOO\Bar\foo();
\FOO\Bar\foo::staticfunction();
\Foo\Bar\FOO;

<?php

// 该函数不能捕获 E_ERROR 错误
set_error_handler(function($errno, $errstr, $errfile, $errline) {
	echo $errstr.PHP_EOL;
});

// 可以捕获 E_ERROR
register_shutdown_function(function() {
    if(is_null($e = error_get_last()) === false) {
        echo $e['message'] . PHP_EOL;
    }
});

<?php
function inverse($x) {
    if(!$x) {
        throw new Exception('Division by zero.');
    }
    return 1/$x;
}

try {
    echo inverse(2).PHP_EOL;
    echo inverse(0).PHP_EOL;
} catch(Exception $e) {
    echo "Caught exception: ", $e->getMessage(). PHP_EOL;
} finally {
    echo "Finally".PHP_EOL;
}

<?php
# 不使用生成器
$start_time=microtime(true);
$array = array();
$result = '';
for($count=1000000; $count--;)
{
  $array[]=$count/2;
}
foreach($array as $val)
{
  $val += 145.56;
  $result .= $val;
}
$end_time=microtime(true);

echo "time: ", bcsub($end_time, $start_time, 4), "\n";
echo "memory (byte): ", memory_get_peak_usage(true), "\n";
?>

<?php
# 使用生成器
$start_time=microtime(true);
$result = '';
function it()
{
  for($count=1000000; $count--;)
  {
    yield $count/2;
  }
}
foreach(it() as $val)
{
  $val += 145.56;
  $result .= $val;
}
$end_time=microtime(true);

echo "time: ", bcsub($end_time, $start_time, 4), "\n";
echo "memory (byte): ", memory_get_peak_usage(true), "\n";
?>

Result: 
            | time   | memory, mb |
----------------------------------|
not gen     | 0.3899 | 44.37891   |
gen         | 0.3679 | 12.375     |

<?php

# 生成键值对形式
$input = <<<'EOF'
1;PHP;Likes dollar signs
2;Python;Likes whitespace
3;Ruby;Likes blocks
EOF;

function input_parser($input) {
    foreach (explode("\n", $input) as $line) {
        $fields = explode(';', $line);
        $id = array_shift($fields);

        yield $id => $fields;
    }
}

foreach(input_parser($input) as $id=>$fields) {
	echo "$id : $fields[0], $fields[1]";
}

# 生成 null 值
# 不传递参数的情况下被调用来生成一个 NULL 值并匹配对一个自动的健名

<?php

function foo(&$var) {
    $var++;
}

$a= 5;
foo($a);
echo $a; // 6

<?php
class foo {
    public $value = 42;

    public function &getValue() {
        return $this->value;
    }
}

$obj = new foo;
// 注意这里也必须使用 & 
$my_value = &$obj->getValue(); // 42

$obj->value = 2;
echo $my_value; // 2

<?php
$a = 1;
$b = &$a;
unset($a);
echo $b; // 1

<?php
// 定义了一个全局变量 $var
$var = &$GLOBALS["var"]