如何根据Cookie值显示内容

I want to display product price in USD and GBP. My default currency is USD. If user come from UK ip range this script will set currency code GBP in cookie.

How to display price based on Cookie value(java-Script method)?

script:

<?php
$con=mysqli_connect("localhost","userip","asdfgh","userip");
$ip = $_SERVER['REMOTE_ADDR'];
$query = "SELECT id FROM ip WHERE '$ip' BETWEEN f AND t"; // check user ip from UK ip range
$result = mysqli_query($con,$query);
if(mysqli_num_rows($result) > 0)
{
  setcookie('currency', 'GBP', time()+604800);
}
mysqli_close($con);
?>

If you want to do it in javascript, you can use the functions below to read/write a cookie.

function read_cookie(name) {
  var arg=name+"=";
  var alen=arg.length;
  var clen=document.cookie.length;
  var i=0;
  while (i<clen){
    var j=i+alen;
    if (document.cookie.substring(i, j)==arg)
       return arguments_cookie(j);
    i=document.cookie.indexOf(" ",i)+1;
    if (i==0) break;
  }
  return null; 
}

function write_cookie(name, val, expires) {
  document.cookie=name+"="+escape(val)+
  ((expires==null) ? "" : ("; expires="+expires.toGMTString()));
}

function arguments_cookie(offset){
    var endstr=document.cookie.indexOf (";", offset);
    if (endstr==-1) endstr=document.cookie.length;
    return unescape(document.cookie.substring(offset, endstr)); 
}

You can read from $_COOKIE global var:

switch ($_COOKIE['currency']) {
  case "GBP": [...]; break;
   default: [...]

more details: http://www.php.net/manual/en/reserved.variables.cookies.php

In PHP you can access cookies through $_COOKIE.

switch($_COOKIE['currency']) {
    case 'GBP':
        $price = <...>;
    break;

    // USD
    default:
    $price = <...>;
}

In JavaScript it's a bit different: http://www.w3schools.com/js/js_cookies.asp

function getCookie(cname)
{
    var name = cname + "=";
    var ca = document.cookie.split(';');

    for(var i=0; i<ca.length; i++) 
    {
        var c = ca[i].trim();
        if (c.indexOf(name)==0) return c.substring(name.length,c.length);
    }

    return "";
}

Note: users can changes cookies in their browser so be aware. A user might change currency to anything trying to break your script.