php HTTP_X_FORWARDED_FOR,HTTP_VIA,REMOTE_ADDR区别总结

　function getIp() {

　　if($_SERVER['HTTP_CLIENT_IP']) {

　　$ip = $_SERVER['HTTP_CLIENT_IP'];    //PHP获取IP

　　} elseif ($_SERVER['HTTP_X_FORWARDED_FOR']) {

　　$ip = $_SERVER['HTTP_X_FORWARDED_FOR'];

　　} else {

　　$ip = $_SERVER['REMOTE_ADDR'];    //PHP获取IP

　　}

　　}

<?php

/*

mktime:2012/9/9

*/
//获取用户真实IP
function get_client_ip() {
if (getenv("HTTP_CLIENT_IP") && strcasecmp(getenv("HTTP_CLIENT_IP"), "unknown"))
$ip = getenv("HTTP_CLIENT_IP");
else
if (getenv("HTTP_X_FORWARDED_FOR") && strcasecmp(getenv("HTTP_X_FORWARDED_FOR"), "unknown"))
$ip = getenv("HTTP_X_FORWARDED_FOR");
else
if (getenv("REMOTE_ADDR") && strcasecmp(getenv("REMOTE_ADDR"), "unknown"))
$ip = getenv("REMOTE_ADDR");
else
if (isset ($_SERVER['REMOTE_ADDR']) && $_SERVER['REMOTE_ADDR'] && strcasecmp($_SERVER['REMOTE_ADDR'], "unknown"))
$ip = $_SERVER['REMOTE_ADDR'];
else
$ip = "unknown";
return ($ip);
}
echo $ip=get_client_ip();//这就是你的ip地址
?>

<?php
$a =array(100,80,50,10,0);
$b = array("c","f","q","e","z");
array_multisort($a,$b);
var_dump($a);
var_dump($b);
?>

array(5) { [0]=> int(0) [1]=> int(10) [2]=> int(50) [3]=> int(80) [4]=> int(100) }
array(5) { [0]=> string(1) “z” [1]=> string(1) “e” [2]=> string(1) “q” [3]=> string(1) “f” [4]=> string(1) “c” }

$arr = array(    
 
    'index'=>array( 'name'=>'首页','order'=>3),
 
    'intro'=>array( 'name'=>'企业概况','order'=>2),
 
    'news'=>array( 'name'=>'新闻动态','order'=>1 ),
 
    'product'=>array( 'name'=>'产品中心','order'=>4 ),
 
    'message'=>array( 'name'=>'访客留言','order'=>7 ),
 
    'position'=>array( 'name'=>'人才招聘','order'=>6),
 
    'contact'=>array( 'name'=>'联系我们','order'=> 5 )
 
);
 
uasort($arr, 'cmp');
 
public function cmp($a, $b){
 
   return $a['order'] - $b['order'];
 
}

$x = 21;
$y = 7;

$z = &$x;
$z = &$y;

int(21)
int(7)
int(7)从结果上看出，$x保持不变，只是$z被改变成了对$y的引用。相当于先unset了$z变量然后赋予了新值。

$z = &$x;
unset($z);
$z = &$y;这其实是比较合理逻辑，就比如下边的代码，我们并不是得到类似于“指向指针的指针(Pointer point to a Pointer)”那样的“引用引用的引用(Reference refer to a Referenece)”，只是多个引用到同一块内容的引用变量。

$x = 21;
$y = &$x;
$z = &$y

$a = array(21, 7);
$b = $a;
$b[0] = 7;
var_dump($a);
echo '<br/>';
var_dump($b);

//Output:
//array(2) { [0]=> int(21) [1]=> int(7) }
//array(2) { [0]=> int(7) [1]=> int(7) }下边我们再来看看如果引用数组中的元素，会有什么异常。

$a = array(21, 7);
$c = & $a[0];
$b = $a;
$b[0]= "21";
$b[1]= "7";

var_dump($a);
echo '<br/>';
var_dump($b);
echo '<br/>';
var_dump($c);
echo '<br/>';

// Output:
// array(2) { [0]=> &string(2) "21" [1]=> int(7) }
// array(2) { [0]=> &string(2) "21" [1]=> string(1) "7" }
// string(2) "21"

unset($b);
unset($c);
var_dump($a);
   
// Output:
//array(2) { [0]=> string(2) "21" [1]=> int(7) }

<?php
//取两个日期内天数差
function SubDay($ntime,$ctime)
{
$dayst = 3600 * 24;
$cday = ceil(($ntime-$ctime)/$dayst);
return $cday;
}
//取当前时间后几天，天数增加单位为1
function AddDay($ntime,$aday)
{
$dayst = 3600 * 24;
$oktime = $ntime + ($aday * $dayst);
return $oktime;
}
//取一周内的某天是星期几

function AddSpeDay($day=0)
{
//$day = isset($day) ? intval($day) : 0;
$daynum = date(‘w’) – $day;
$oktime = time() – (3600 * 24 * $daynum);
return $oktime;
}

#附php取当前时间的方法

//取当前时间，格式为2009-10-23 14:20:35

function GetDateTimeMk($mktime)
{
return MyDate(‘Y-m-d H:i:s’,$mktime);
}

//取当前时间，格式为2009-10-23

function GetDateMk($mktime)
{
return MyDate(“Y-m-d”,$mktime);
}

?>

abstract class Operation{
    abstract public  function getValue($num1,$num2);
    public  function getAttr(){
        return 1;
    }
}
class Add extends Operation{
    public function getValue($num1, $num2){       
        return $num1+$num2;
    }
}

class Sub extends Operation{
    public function getValue($num1, $num2){
        return $num1-$num2;
    }
}

class Factory{
    public static function CreateObj($operation){
       
        switch ($operation){
            case '+': return new Add();
            case '-': return new Sub();
        }
       
    }
}

$Op=Factory::CreateObj('-');
echo $Op->getValue(3, 6);

<?php
interface IUser
{
  function getName();
}

class User implements IUser
{
  public static function Load( $id )
  {
        return new User( $id );
  }

  public static function Create( )
  {
        return new User( null );
  }

  public function __construct( $id ) { }

  public function getName()
  {
    return "Jack";
  }
}

$uo = User::Load( 1 );
echo( $uo->getName()."n" );
?>

index.php

<?php
include_once("f.inc.php");
$f=new factory;
$t1=&$f->create('T1');
echo $t1->getName();
echo $config;
?>
f.inc.php

<?php
class factory
{
 function factory()
 {
  $this->mClasses=array('T1'=>'t1.inc.php','T2'=>'t2.inc.php');
 }
 function &create($class)
 {
  if (!class_exists($class))
  {
   require_once($this->mClasses[$class]);
  }
  return new $class;
 }
}
?>
t1.inc.php

<?php
global $config;
$config='surfchen';
class T1
{
 var $mName='name::T1';
 function getName()
 {
  return $this->mName;
 }
}
?>
t2.inc.php

<?php
class T2
{
 function T2()
 {
  echo 't2 is ok';
 }
}
?>

class Mysql{
    public static $conn;
    public static function getInstance(){
        if (!self::$conn){
            new self();
            return self::$conn;
        }else {
            return self::$conn;
        }
       
    }
    private  function __construct(){   
        self::$conn=  "mysql_connect:";//    mysql_connect('','','')   
    }
   
    public function __clone()
    {
        trigger_error("Only one connection");
    }
}

echo Mysql::getInstance();
echo Mysql::getInstance();