进入网站之前请先达成用户协议-PHP，重定向，Cookie

Question

I need some help with php redirection, cookies, etc. To specify what I exactly want it to do please take a look at description:

I have created files: index.php, contact.php, info.php etc. .. I have also make agecheck.php

And so I what it to, when you go to index.php, contact.php, info.php, etc., then it shall redirect to agecheck.php, where you have the opportunity to click on two buttons YES or NO . If you click YES , it returns you to the previous page that you were redirected from, and if you click NO , it shall just stay on agecheck.php with a note that says:

you have to be 18 to enter the site.

But I will also like to have cookie on, that will remembers if you had clicked YES before, so you shouldn't have to be redirected every time when you enter the site.

Answer 1

You can set a cookie or use a session, but this will not work if your user's browser does not accept cookies.

The advantage of a cookie is that you can set it to continue to exist after the user closes the browser (but the user can disable this behavior)

session (also requires that user allows cookies)

<?php
// This check must be at the top of every page, e.g. through an include
session_start();
if(!isset($_SESSION['agecheck']) || !$_SESSION['agecheck']){
    $_SESSION['agecheck_ref'] = $_SERVER['REQUEST_URI'];
    header("Location: http://your.site/agecheck.php");
    die();
}
?>

<?php
// You need to set the session variable in agecheck.php
session_start();
if($age >= 18){
    $_SESSION['agecheck'] = true;
    if(!isset($_SESSION['agecheck_ref'])) {
        $_SESSION['agecheck_ref'] = "/";
    }
    header("Location: http://your.site" . $_SESSION['agecheck_ref']);
}
?>

Or similar with cookies, which you can set to last longer

<?php
// This check must be at the top of every page, e.g. through an include
session_start();
if(!isset($_COOKIE['agecheck']) || $_COOKIE['agecheck'] != "true"){
    $_SESSION['agecheck_ref'] = $_SERVER['REQUEST_URI'];
    header("Location: http://your.site/agecheck.php");
    die();
}
?>

<?php
// You need to set the cookie in agecheck.php
session_start();
if($age >= 18){
    setcookie("agecheck", "true", time()+60*60*24*90); // Remember answer for 90 days
    if(!isset($_SESSION['agecheck_ref'])) {
        $_SESSION['agecheck_ref'] = "/";
    }
    header("Location: http://your.site" . $_SESSION['agecheck_ref']);
}
?>

Answer 2

To redirect, use header() :

header("Location: agecheck.php");

Then to check which button is pressed, you will have to use some JavaScript:

<script type = "text/javascript">
function yesbutton()
{
window.location.assign("Yourpage.php");
}
function nobutton()
{
document.write("You must be over 18 to view this page");
}
</script>

<input type = "button" onclick = "yesbutton()" value = "yes">
<input type = "button" onclick = "nobutton()" value = "no">

Then you can set a JavaScript cookie in the yesbutton() function.

The reason for using JScript is that the buttons are on the client side, and PHP is on the server side. This means they can't interact.