<?php switch ($foo): ?>
    <?php case 1: ?>
    ...
<?php endswitch ?>

<?php switch ($foo): ?>
<?php case 1: ?>
    ...
<?php endswitch ?>

<?php

/* 不正确的使用方法： */
if($a > $b):
    echo $a." is greater than ".$b;
else if($a == $b): // 将无法编译
    echo "The above line causes a parse error.";
endif;


/* 正确的使用方法： */
if($a > $b):
    echo $a." is greater than ".$b;
elseif($a == $b): // 注意使用了一个单词的 elseif
    echo $a." equals ".$b;
else:
    echo $a." is neither greater than or equal to ".$b;
endif;

?>

for (expr1; expr2; expr3)
    statement

/* example 2 */    
for ($i = 1; ; $i++) {
    if ($i > 10) {
        break;
    }
    echo $i;
}

/* example 3 */    
$i = 1;
for (;;) {
    if ($i > 10) {
        break;
    }
    echo $i;
    $i++;
}

/* example 4 */    
for ($i = 1, $j = 0; $i <= 10; $j += $i, print $i, $i++);

/* example */
$people = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
for($i = 0, $size = count($people); $i < $size; ++$i)
{
    print $people[$i];
}

<?php
for($col = 'R'; $col != 'AD'; $col++) {
    echo $col.' ';
}

//returns: R S T U V W X Y Z AA AB AC

//Take note that you can't use $col < 'AD'. It only works with !=
//Very convenient when working with excel columns.
?>

<?php
$arr = array(1, 2, 3, 4);
foreach ($arr as &$value) {
    $value = $value * 2;
}
// $arr is now array(2, 4, 6, 8)
unset($value); // 最后取消掉引用
?>

<?php
$arr = array("one", "two", "three");
reset($arr);
while (list(, $value) = each($arr)) {
    echo "Value: $value<br>\n";
}

foreach ($arr as $value) {
    echo "Value: $value<br />\n";
}
?>

<?php
$arr = array("one", "two", "three");
reset($arr);
while (list($key, $value) = each($arr)) {
    echo "Key: $key; Value: $value<br />\n";
}

foreach ($arr as $key => $value) {
    echo "Key: $key; Value: $value<br />\n";
}
?>

<?php
$array = [
    [1, 2],
    [3, 4],
];    
foreach ($array as list($a, $b)) {
    // $a contains the first element of the nested array,
    // and $b contains the second element.
    echo "A: $a; B: $b\n";
}
?>

A: 1; B: 2
A: 3; B: 4

<?php
$i = 0;
while (++$i) {
    switch ($i) {
    case 5:
        echo "At 5<br />\n";
        break 1;  /* 只退出 switch. */
    case 10:
        echo "At 10; quitting<br />\n";
        break 2;  /* 退出 switch 和 while 循环 */
    default:
        break;
    }
}
?>

<?php 
echo "hello";
if (true) break;
echo " world";
?>

<?php
$i = 0;
while ($i++ < 5) {
    echo "Outer<br />\n";
    while (1) {
        echo "Middle<br />\n";
        while (1) {
            echo "Inner<br />\n";
            continue 3;
        }
        echo "This never gets output.<br />\n";
    }
    echo "Neither does this.<br />\n";
}
?>

<?php

    for( $i = 0; $i < 3; ++ $i )
    {
        echo ' [', $i, '] ';
        switch( $i )
        {
            case 0: echo 'zero'; break;
            case 1: echo 'one' ; XXXX;
            case 2: echo 'two' ; break;
        }
        echo ' <' , $i, '> ';
    }

?>

For XXXX I filled in

- continue 1//[0] zero <0>  [1] one <1>  [2] two <2>
- continue 2//[0] zero <0>  [1] one [2] two <2>
- break 1//[0] zero <0>  [1] one <1>  [2] two <2>
- break 2//[0] zero <0>  [1] one

<?php
$a = 0;

if(++$a == 3) echo 3;
elseif(++$a == 2) echo 2;
elseif(++$a == 1) echo 1;
else echo "No match!";

// Outputs: 2

$a = 0;

switch(++$a) {
    case 3: echo 3; break;
    case 2: echo 2; break;
    case 1: echo 1; break;
    default: echo "No match!"; break;
}

// Outputs: 1
?>

declare (directive)
    statement

<?php
// these are the same:

// you can use this:
declare(ticks=1) {
    // entire script here
}

// or you can use this:
declare(ticks=1);
// entire script here
?>

<?php

declare(ticks=1);

// A function called on each tick event
function tick_handler()
{
    echo "tick_handler() called\n";
}

register_tick_function('tick_handler');

$a = 1;

if ($a > 0) {
    $a += 2;
    print($a);
}
/*
tick_handler() called
tick_handler() called
tick_handler() called
3tick_handler() called
 */
?>

<?php

function tick_handler()
{
  echo "tick_handler() called\n";
}

$a = 1;
tick_handler();

if ($a > 0) {
    $a += 2;
    tick_handler();
    print($a);
    tick_handler();
}
tick_handler();

?>

<?php
declare(encoding='ISO-8859-1');
// code here
?>

file.php
<?php 
$a = ['aa'];
 ?>

php.php
<?php 
return ['aa'];
 ?>

<?php 
if (false) {
    require 'file';
    require('file.php');
}
//include 'file';//Warning
var_export(include('file.php'));echo "\r\n";
if (true) {
    echo require 'file.php', "\r\n";
    var_dump(@include 'file');echo "\r\n";
    var_dump(require 'php.php');echo "\r\n";
    var_dump((include('php.php')) == ['aa']);echo "\r\n";//注意括号，等同(include 'php.php') == ['aa']
    var_dump(include('php.php') == ['aa']);echo "\r\n";//等同于include(('php.php') == ['aa'])
    require 'file';
}
echo 'End';
/*
1
1
bool(false)

array(1) {
  [0]=>
  string(2) "aa"
}

bool(true)

PHP Warning:  include(): Filename cannot be empty in D:\php\test\test.php on line 13

Warning: include(): Filename cannot be empty in D:\php\test\test.php on line 13
PHP Warning:  include(): Failed opening '' for inclusion (include_path='.;C:\php\pear') in D:\php\test\test.php on line 13

Warning: include(): Failed opening '' for inclusion (include_path='.;C:\php\pear') in D:\php\test\test.php on line 13
bool(false)

PHP Warning:  require(file): failed to open stream: No such file or directory in D:\php\test\test.php on line 14

Warning: require(file): failed to open stream: No such file or directory in D:\php\test\test.php on line 14
PHP Fatal error:  require(): Failed opening required 'file' (include_path='.;C:\php\pear') in D:\php\test\test.php on line 14

Fatal error: require(): Failed opening required 'file' (include_path='.;C:\php\pear') in D:\php\test\test.php on line 14
 */
 ?>

<?php
$string = get_include_contents('somefile.php');

function get_include_contents($filename) {
    if (is_file($filename)) {
        ob_start();
        include $filename;
        $contents = ob_get_contents();
        ob_end_clean();
        return $contents;
    }
    return false;
}

?>

<?php 
var_dump(include_once 'file.php'); // int(1)
var_dump(include_once 'file.php'); // bool(true)
 ?>

<?php
for($i=0,$j=50; $i<100; $i++) {
  while($j--) {
    if($j==17) goto end; 
  }  
}
echo "i = $i";
end:
echo 'j hit 17';
?>

//j hit 17

<?php
goto loop;
for($i=0,$j=50; $i<100; $i++) {
  while($j--) {
    loop:
  }
}
echo "$i = $i";
?>

Fatal error: 'goto' into loop or switch statement is disallowed in
script on line 2

Remember if you are not a fan of wild labels hanging around you are free to use braces in this construct creating a slightly cleaner look. 
Labels also are always executed and do not need to be called to have their associated code block ran. A purposeless example is below.
<?php 

$headers = Array('subject', 'bcc', 'to', 'cc', 'date', 'sender'); 
$position = 0; 

hIterator: { 

    $c = 0; 
    echo $headers[$position] . PHP_EOL; 

    cIterator: { 
        echo ' ' . $headers[$position][$c] . PHP_EOL; 

        if(!isset($headers[$position][++$c])) { 
            goto cIteratorExit; 
        } 
        goto cIterator; 
    } 

    cIteratorExit: { 
        if(isset($headers[++$position])) { 
            goto hIterator; 
        } 
    } 
} 
?>

<?php    
$makefoo = true;

/* 不能在此处调用foo()函数，
   因为它还不存在，但可以调用bar()函数。*/    
bar();

if ($makefoo) {
  function foo()
  {
    echo "I don't exist until program execution reaches me.\n";
  }
}    
/* 现在可以安全调用函数 foo()了，
   因为 $makefoo 值为真 */    
if ($makefoo) foo();

function bar()
{
  echo "I exist immediately upon program start.\n";
}

?>

<?php
function foo() {
  function bar() {
    echo "I don't exist until foo() is called.\n";
  }
}

/* 现在还不能调用bar()函数，因为它还不存在 */
foo();

/* 现在可以调用bar()函数了，因为foo()函数
   的执行使得bar()函数变为已定义的函数 */    
bar();

?>

<?php
 function test(boolean $param) {}
 test(true);
 ?>

Fatal error: Uncaught TypeError: Argument 1 passed to test() must be an instance of boolean, boolean given, called in - on line 1 and defined in -:1

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

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

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

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

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

<?php
function total_intervals($unit, DateInterval ...$intervals) {
    $time = 0;
    foreach ($intervals as $interval) {
        $time += $interval->$unit;
    }
    return $time;
}

$a = new DateInterval('P1D');
$b = new DateInterval('P2D');
echo total_intervals('d', $a, $b).' days';//3 days

// This will fail, since null isn't a DateInterval object.
echo total_intervals('d', null);
//Catchable fatal error: Argument 2 passed to total_intervals() must be an instance of DateInterval, null given, called in - on line 14 and defined in - on line 2
?>

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

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

<?php
function square($num) {
    $sum = $num * $num;
}
function square2($num) {
    $sum = $num * $num;
    return;
}
var_dump(square(4));   // NULL
var_dump(square2(4));   // NULL
?>

<?php
function &returns_reference()
{
    return $someref;
}

$newref =& returns_reference();
?>

<?php
class Foo
{
    static $variable = 'static property';
    static function Variable() {
        echo 'Method Variable called';
    }
}

echo Foo::$variable; // This prints 'static property'. It does need a $variable in this scope.
$variable = "Variable";
Foo::$variable();  // This calls $foo->Variable() reading $variable in this scope.

?>

<?php
class Foo
{
    static function bar()
    {
        echo "bar\n";
    }
    function baz()
    {
        echo "baz\n";
    }
}

$func = array("Foo", "bar");
$func(); // prints "bar"
$func = array(new Foo, "baz");
$func(); // prints "baz"
$func = "Foo::bar";
$func(); // prints "bar" as of PHP 7.0.0; prior, it raised a fatal error
?>

<?php
$message = 'hello';

// 没有 "use"
$example = function () {
    var_dump($message);
};
echo $example();
//Notice: Undefined variable: message in /example.php on line 6
//NULL

// 继承 $message
$example = function () use ($message) {
    var_dump($message);
};
echo $example();//string(5) "hello"

$message = 'world';
echo $example();//string(5) "hello"

// Reset message
$message = 'hello';

$example = function () use (&$message) {
    var_dump($message);
};
echo $example();//string(5) "hello"

$message = 'world';
echo $example();//string(5) "world"

// Closures can also accept regular arguments
$example = function ($arg) use ($message) {
    var_dump($arg . ' ' . $message);
};
$example("hello");//string(11) "hello world"
?>

<?php

class Test
{
    public function testing()
    {
        return function() {
            var_dump($this);
        };
    }
    public function testing2()
    {
        return static function() {
            var_dump($this);
        };
    }
}

$object = new Test;
$function = $object->testing();
$function();
$object->testing2()();
?>

object(Test)#1 (0) {
}
PHP Notice:  Undefined variable: this in D:\php\test\test.php on line 13

Notice: Undefined variable: this in D:\php\test\test.php on line 13
NULL

PHP Notice:  Undefined variable: this in D:\php\test\test.php on line 7

Notice: Undefined variable: this in D:\php\test\test.php on line 7
NULL

PHP Parse error:  syntax error, unexpected T_FUNCTION, expecting T_PAAMAYIM_NEKUDOTAYIM in D:\php\test\test.php on line 12

Parse error: syntax error, unexpected T_FUNCTION, expecting T_PAAMAYIM_NEKUDOTAYIM in D:\php\test\test.php on line 12