PHP标头位置重定向不起作用

Question

No idea why this is not working. Here is the code:

if ((isset($_POST['cancel'])) && ($_POST['cancel'] == 'cancel'))
{
    header('Location: page1.php');
    echo $_POST['cancel'];
}

Instead of redirecting the page, this output's cancel to the webpage. It skipped over the redirect. Why? How can I fix this? page1.php is a real page located in the same folder as the current page. The above code is the very first lines of the php file. Nothing before it. Nothing. Not even whitespace.

Answer 1

This is likely a problem generated by the headers being already sent.

Why

This occurs if you have echoed anything before deciding to redirect. If so, then the initial (default) headers have been sent and the new headers cannot replace something that's already in the output buffer getting ready to be sent to the browser.

Sometimes it's not even necessary to have echoed something yourself:

• if an error is being outputted to the browser it's also considered content so the headers must be sent before the error information;
• if one of your files is encoded in one format (let's say ISO-8859-1) and another is encoded in another (let's say UTF-8 with BOM) the incompatibility between the two encodings may result in a few characters being outputted;

Let's check

To test if this is the case you have to enable error reporting: error_reporting(E_ALL); and set the errors to be displayed ini_set('display_errors', TRUE); after which you will likely see a warning referring to the headers being already sent.

Let's fix

Fixing this kinds of errors:

• writing your redirect logic somewhere in the code before anything is outputted;
• using output buffers to trap any outgoing info and only release it at some point when you know all redirect attempts have been run;
• Using a proper MVC framework they already solve it;

More

MVC solves it both functionally by ensuring that the logic is in the controller and the controller triggers the display/rendering of a view only at the end of the controllers. This means you can decide to do a redirect somewhere within the action but not withing the view.

Answer 2

I have experienced that kind of issue before and now I'm not using header('Location: pageExample.php'); anymore, instead I'm using javascript's document.location .

Change your:

header('Location: page1.php');

To something like this:

echo "<script type='text/javascript'> document.location = 'page1.php'; </script>";

And what is the purpose of echo $_POST['cancel']; by the way?, just delete that line if what you want is just the redirection. I've been using that <script> every time and it doesn't fail me. :-)

Answer 3

Use @obstart or try to use Java Script

put your obstart(); into your top of the page

if ((isset($_POST['cancel'])) && ($_POST['cancel'] == 'cancel'))
{
    header('Location: page1.php');
    exit();
}

---

If you use Javascript Use window.location.href

window.location.href example:

 if ((isset($_POST['cancel'])) && ($_POST['cancel'] == 'cancel'))
    {
        echo "<script type='text/javascript'>window.location.href = 'page1.php';</script>"
        exit();
    }

Answer 4

I had also the similar issue in godaddy hosting. But after putting ob_start(); at the beginning of the php page from where page was redirecting, it was working fine.

Please find the example of the fix:

fileName: index.php

<?php
ob_start();
...
header('Location: page1.php');
...
ob_end_flush();
?>

Answer 5

For me also it was not working. Then i try with javascript inside php like

echo "<script type='text/javascript'>  window.location='index.php'; </script>";

This will definitely working.

Answer 6

I had similar problem... solved by adding ob_start(); and ob_end_flush(); ...

<?php 
ob_start();


require 'engine/vishnuHTML.class.php';
require 'engine/admin/login.class.php';

$html=new vishnuHTML();
 (!isset($_SESSION))?session_start():"";

/* blah bla Code
...........
...........
 */

</div>
</div>
<?php
}



ob_end_flush();
?>

Think of ob_start() as saying "Start remembering everything that would normally be outputted, but don't quite do anything with it yet."

ob_end_clean() or ob_flush(), which either stops saving things and discards whatever was saved, or stops saving and outputs it all at once, respectively.

Answer 7

Pekka answered my question in the comments. He didn't post an answer, so I am now. Use the exit() method after the header redirect. For some reason the rest of the code of the page continues to execute after the header() method redirect. When the rest of the code executes, the echo statement is outputted to the page. And you can't redirect using the header function after you output to the page. To avoid rest of the code from executing, use exit() . Thanks Pekka.

UPDATE: When using the web browser Internet Explorer, I have noticed that $_POST['cancel'] is not reliable. I am not exactly sure why this is, but I suspect IE posts additional variables on a form submit, specifically the variable 'cancel' is posted. I solved this by using a variable name other than 'cancel'. The combination of using exit() and a unique variable name is working for me.

Answer 8

Try adding

ob_start();

at the top of the code ie before the include statement.

Answer 9

Neer to specify exit code here so php not execute further

if ((isset($_POST['cancel'])) && ($_POST['cancel'] == 'cancel'))
{
    header('Location: page1.php');        
    exit(0); // require to exit here 
}

Answer 10

确保在页面顶部启动<?php标记时，在<?php之前不要留空格。

Answer 11

Be very careful with whitespace and other stuff that may affect the "output" already done. I certainly know this but still suffered from the same problem. My whole "Admin.php"-file had some spaces after the closing php-tag ?> down the bottom on the last row :)

Easily discovered by adding...

error_reporting(E_ALL);

...which told me which line of code that generated the output.

Answer 12

Try this, Add @ob_start() function in top of the page,

if ((isset($_POST['cancel'])) && ($_POST['cancel'] == 'cancel'))
{
    header('Location: page1.php');
    exit();
}

Answer 13

Use the following code:

if(isset($_SERVER['HTTPS']) == 'on')
{

    $self = $_SERVER['SERVER_NAME'].$_SERVER['REQUEST_URI'];
    ?>

     <script type='text/javascript'>
     window.location.href = 'http://<?php echo $self ?>';
     </script>"
     <?php

     exit();
}
?>

Answer 14

put < ?php tag on the top of your file (starting on frist line of document)

not:

--- Blank space or something ---
<?php

but:

<?php
..your code
header('Location: page1.php');
...