深入分析PHP运算符优先级

$array1 = array(1, 2);
$array2 = array(3, 4);

$result = empty($array1) == 3 ? $array1 : $array2;

<?php
if ($a = 100 && $b = 200) {
     var_dump($a, $b);
}

<?php
$x=TRUE;
$y=FALSE;
$z=$y OR $x; ?>
代码2：
<?php
$x=TRUE;
$y=FALSE;
$z=$y || $x;
?>

$z = ($y OR $x);

$z = ($y || $x);

<?php
// == 是一个操作符，它检测两个变量是否相等，并返回一个布尔值
if ( $action  ==  "show_version" ) {
    echo  "The version is 1.23" ;
}

// 这样做是不必要的...
if ( $show_separators  ==  TRUE ) {
    echo  "<hr>n" ;
}

// ...因为可以使用下面这种简单的方式：
if ( $show_separators ) {
    echo  "<hr>n" ;
}
?>

/* 例子：数据库连接职责的集中控制 */
class Database {
 
private $_db;
static $_instance;
 
private function __construct() {
$this->_db = pg_connect('dbname=example_db');
}
 
private __clone() {};
 
public static function getInstance() {
 if(! (self::$_instance instanceof self) )
 {
 self::$_instance = new self();
 }
 return self::$_instance;
 
}
 
public function query($sql) {
// 使用 $this->_db 执行一个查询
return pg_query($this->_db, $sql);
}
}

//定义编码
header( Content-Type:text/html;charset=utf-8 );
//Atom
header(Content-type: application/atom+xml);
//CSS
header(Content-type: text/css);
//Javascript
header(Content-type: text/javascript);
//JPEG Image
header(Content-type: image/jpeg);
//JSON
header(Content-type: application/json);
//PDF
header(Content-type: application/pdf);
//RSS
header(Content-Type: application/rss+xml; charset=ISO-8859-1);
//Text (Plain)
header(Content-type: text/plain);
//XML
header(Content-type: text/xml);
// ok
header(HTTP/1.1 200 OK);
//设置一个404头:
header(HTTP/1.1 404 Not Found);
//设置地址被永久的重定向
header(HTTP/1.1 301 Moved Permanently);
//转到一个新地址
header(Location: http://www.example.org/);
//文件延迟转向:
header(Refresh: 10; url=http://www.example.org/);
print You will be redirected in 10 seconds;
//当然，也可以使用html语法实现
// <meta http-equiv="refresh" content="10;http://www.example.org/ />
// override X-Powered-By: PHP:
header(X-Powered-By: PHP/4.4.0);
header(X-Powered-By: Brain/0.6b);
//文档语言
header(Content-language: en);
//告诉浏览器最后一次修改时间
$time = time() - 60; // or filemtime($fn), etc
header(Last-Modified: .gmdate(D, d M Y H:i:s, $time). GMT);
//告诉浏览器文档内容没有发生改变
header(HTTP/1.1 304 Not Modified);
//设置内容长度
header(Content-Length: 1234);
//设置为一个下载类型
header(Content-Type: application/octet-stream);
header(Content-Disposition: attachment; filename="example.zip");
header(Content-Transfer-Encoding: binary);
// load the file to send:
readfile(example.zip);
// 对当前文档禁用缓存
header(Cache-Control: no-cache, no-store, max-age=0, must-revalidate);
header(Expires: Mon, 26 Jul 1997 05:00:00 GMT); // Date in the past
header(Pragma: no-cache);
//设置内容类型:
header(Content-Type: text/html; charset=iso-8859-1);
header(Content-Type: text/html; charset=utf-8);
header(Content-Type: text/plain); //纯文本格式
header(Content-Type: image/jpeg); //JPG***
header(Content-Type: application/zip); // ZIP文件
header(Content-Type: application/pdf); // PDF文件
header(Content-Type: audio/mpeg); // 音频文件
header(Content-Type: application/x-shockw**e-flash); //Flash动画

//显示登陆对话框
header(HTTP/1.1 401 Unauthorized);
header(WWW-Authenticate: Basic realm="Top Secret");
print Text that will be displayed if the user hits cancel or ;
print enters wrong login data;

$arr = array(
    '0'=>array(
            'firmware'=>'f1',
            'version'=>'1',
        ),
    '1'=>array(
            'firmware'=>'f1',
            'version'=>'2',
        ),
    '2'=>array(
            'firmware'=>'f1',
            'version'=>'3',
        ),
    '3'=>array(
            'firmware'=>'f2',
            'version'=>'1',
        ),
    '4'=>array(
            'firmware'=>'f2',
            'version'=>'2',
        ),
    );
    $new_arr  =  array();
    foreach ($arr as $row ){
        $new_arr[$row['firmware']][] = $row['version'];
    }
    var_dump($new_arr);
转换后

Array
(
    [f1] => Array
        (
            [0] => 1
            [1] => 2
            [2] => 3
        )

    [f2] => Array
        (
            [0] => 1
            [1] => 2
        )

)

class Bar
{
    public function test() {
        $this->testPrivate();
        $this->testPublic();
    }

    public function testPublic() {
        echo "Bar::testPublicn";
    }
   
    private function testPrivate() {
        echo "Bar::testPrivaten";
    }
}

class Foo extends Bar
{
    public function testPublic() {
        echo "Foo::testPublicn";
    }
   
    private function testPrivate() {
        echo "Foo::testPrivaten";
    }
}

$myFoo = new Foo();
$myFoo->test();
// 运行结果
// Bar->testPrivate
// Foo->testPublic

header('Access-Control-Allow-Origin: *'); 
header('Access-Control-Allow-Origin: ccdd.com');
codeigniter指定地址实现HTTPS访问管理
//启动hooks
//app/config/config.php
$config['enable_hooks'] = TRUE;

//hooks配置
///app/config/hooks.php
$hook['post_controller_constructor'][] = array(
        'function' => 'check_ssl',
        'filename' => 'ssl.php',
        'filepath' => 'hooks',
    );

//插件编写
//app/hooks/ssl.php
function check_ssl(){
$CI =& get_instance();
$class = $CI->router->fetch_class();
$method = $CI->router->fetch_method();

$ssl = $CI->config->item('ssl_class_method');  
$partial = $CI->config->item('no_ssl_class_method');   

if(in_array($class.'/'.$method,$ssl)){
    //force_ssl();
    $CI =&get_instance();
    $CI->config->config['base_url'] = str_replace('http://', 'https://', $CI->config->config['base_url']);
    if ($_SERVER['SERVER_PORT'] != 443) redirect($CI->uri->uri_string());
}
else if(in_array($class.'/'.$method,$partial))
{
        return;
    }
    else{
        //unforce_ssl
        $CI =&get_instance();
        $CI->config->config['base_url'] = str_replace('https://', 'http://', $CI->config->config['base_url']);
        if ($_SERVER['SERVER_PORT'] == 443) redirect($CI->uri->uri_string());
    }
}

//config 配置需要使用https的 class method
//app/config/config.php
$config['ssl_class_method'] = array(
    'U_class/A_method',
    'V_class/B_method',
    'W_class/C_method',
    'X_class/D_method',
    ); //强制使用ssl
$config['no_ssl_class_method'] = array();

include_once("./includefile.php");

include_once(dirname(__FILE__) ."/includefile.php");

define('BASE_PATH',str_replace('\\','/',realpath(dirname(__FILE__).'/'))."/");

echo BASE_PATH;

$PHP_SELF=$_SERVER['PHP_SELF'];

$url='http://'.$_SERVER['HTTP_HOST'].substr($PHP_SELF,0,strrpos($PHP_SELF,'/')+1);

echo $url;