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Sep 4th, 2007

PHP Warning: Cannot modify header information - headers already sent by (output .....

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Hello please help me troubleshooting this. i got this error in my login.. pleaaaaase. below is the error that prompts me when i login:

PHP Warning: Cannot modify header information - headers already sent by (output started at D:\HostingSpaces\spindev\spindev.spinweb.ph\wwwroot\YPS\login\login.php:9) in D:\HostingSpaces\spindev\spindev.spinweb.ph\wwwroot\YPS\login\login.php on line 71 PHP Warning: Cannot modify header information - headers already sent by (output started at D:\HostingSpaces\spindev\spindev.spinweb.ph\wwwroot\YPS\login\login.php:9) in D:\HostingSpaces\spindev\spindev.spinweb.ph\wwwroot\YPS\login\login.php on line 72 PHP Warning: Cannot modify header information - headers already sent by (output started at D:\HostingSpaces\spindev\spindev.spinweb.ph\wwwroot\YPS\login\login.php:9) in D:\HostingSpaces\spindev\spindev.spinweb.ph\wwwroot\YPS\login\login.php on line 75

Here is my code: please tell me what's going wrong. thanks.

<?php
// Connects to your Database
mysql_connect("spindev.spinweb.ph", "spindev_ypsuser", "yps123") or die(mysql_error());
mysql_select_db("spindev_ypsnew") or die(mysql_error());
//checks cookies to make sure they are logged in
if(isset($_COOKIE['ID_my_site']))
{
$username = $_COOKIE['ID_my_site'];
$pass = $_COOKIE['Key_my_site'];
$check = mysql_query("SELECT * FROM users WHERE username = '$username'")or die(mysql_error());
while($info = mysql_fetch_array( $check ))
{
//if the cookie has the wrong password, they are taken to the login page
if ($pass != $info['password'])
{ header("Location: login.php");
}
//otherwise they are shown the admin area
else
{
echo "Admin Area<p>";
echo "Your Content<p>";
echo "<a href=logout.php>Logout</a>";
}
}
}
else
//if the cookie does not exist, they are taken to the login screen
{
header("Location: login.php");
}
?>

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dudegio

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since May 2007

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Sep 4th, 2007

Re: PHP Warning: Cannot modify header information - headers already sent by (output .

From first glance it looks like you've placed echo above the header location script.

Headers must be parsed before any HTML, and for some reason (Unknown by me, but I'm sure others can answer why) certain hosts don't like it when you place any HTML above header tags.

I would stick the HTML below the php code, specifically below the Header("Location: login.php") script.

Eg:

php Syntax (Toggle Plain Text)
<?php
// Connects to your Database
mysql_connect("spindev.spinweb.ph", "spindev_ypsuser", "yps123") or die(mysql_error());
mysql_select_db("spindev_ypsnew") or die(mysql_error());
//checks cookies to make sure they are logged in
if(isset($_COOKIE['ID_my_site']))
{
    $username = $_COOKIE['ID_my_site'];
    $pass = $_COOKIE['Key_my_site'];
    $check = mysql_query("SELECT * FROM users WHERE username = '$username'")or die(mysql_error());
    while($info = mysql_fetch_array( $check ))
    {
        //if the cookie has the wrong password, they are taken to the login page
        if ($pass != $info['password'])
        { 
            header("Location: login.php");
        }
        //otherwise they are shown the admin area
        else
        {
            //echo "Admin Area<p>";
            //echo "Your Content<p>";
            //echo "<a href=logout.php>Logout</a>";
        }
    }
}
else
//if the cookie does not exist, they are taken to the login screen
{
    header("Location: login.php");
}
?>
<h1>Admin Area</h1>
<p>Your content</p>
<p><a href="logout.php">Logout</a>
<?php
// Connects to your Database
mysql_connect("spindev.spinweb.ph", "spindev_ypsuser", "yps123") or die(mysql_error());
mysql_select_db("spindev_ypsnew") or die(mysql_error());
//checks cookies to make sure they are logged in
if(isset($_COOKIE['ID_my_site']))
{
    $username = $_COOKIE['ID_my_site'];
    $pass = $_COOKIE['Key_my_site'];
    $check = mysql_query("SELECT * FROM users WHERE username = '$username'")or die(mysql_error());
    while($info = mysql_fetch_array( $check ))
    {
        //if the cookie has the wrong password, they are taken to the login page
        if ($pass != $info['password'])
        { 
            header("Location: login.php");
        }
        //otherwise they are shown the admin area
        else
        {
            //echo "Admin Area<p>";
            //echo "Your Content<p>";
            //echo "<a href=logout.php>Logout</a>";
        }
    }
}
else
//if the cookie does not exist, they are taken to the login screen
{
    header("Location: login.php");
}
?>
<h1>Admin Area</h1>
<p>Your content</p>
<p><a href="logout.php">Logout</a>

I could be completely off the mark, since it is late. I'd suggest tweaking the order of your conditions so that if an error occurs the user is directed away from the page, otherwise the html at the end loads on a successful log in.

WhiteLeo

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Sep 4th, 2007

Re: PHP Warning: Cannot modify header information - headers already sent by (output .

try placing this at the top of your page:
<? ob_start(); ?>

then at the bottom of the page place this line of code:

<? ob_flush(); ?>

JeniF

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since Aug 2007

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Sep 4th, 2007

Re: PHP Warning: Cannot modify header information - headers already sent by (output .....

Thanks to both of you. I have tried your solution JeniF and the login script works. Thanks a lot. I will try to implement your solutions as well WhiteLeo so that i do have lot of references if it works. Thank you very much again.

Last edited by dudegio; Sep 4th, 2007 at 11:27 pm.

dudegio

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Sep 11th, 2007

Re: PHP Warning: Cannot modify header information - headers already sent by (output .

Really Thank you for your Valuable info.....

sujithfem

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Feb 19th, 2008

Re: PHP Warning: Cannot modify header information - headers already sent by (output .

Click to Expand / Collapse Quote originally posted by JeniF ...

try placing this at the top of your page:
<? ob_start(); ?>

then at the bottom of the page place this line of code:

<? ob_flush(); ?>

_________________________________________________
Thank you so much JeniF. I have been receiving a similar error for days now, and have been unable to complete a class assignment. Popped your suggestion in, and it now works. My elation is directly correlated to my previous frustration, and I just wanted to take the time to say thanks. Have a good one.

(Incidentally, if you get the time, what exactly is the recommended code doing?)

TaiShar

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Feb 19th, 2008

Re: PHP Warning: Cannot modify header information - headers already sent by (output .....

Quote ...

(Incidentally, if you get the time, what exactly is the recommended code doing?)

ob_start() . Its turning on the output buffer. So any output is kept in the buffer. And ob_flush() is to flush the buffer

nav33n

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Purple hazed!

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since Nov 2007

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May 19th, 2008

Re: PHP Warning: Cannot modify header information - headers already sent by (output .....

I had a problem with the "headers already sent" too at my http://www.maxi-pedia.com website. In my case, it was caused by a blank line at the beginning of one *.inc file. PHP seems to have problems with extra spaces here and there.

Check all your *.inc files to make sure you do not have closing ?> in any of them. Closing ?> is not needed in your *.inc files. Check all your *.php files to make sure you do not have blank lines at the beginning or at the end.

If you are working in a CMS, then it may be caused by some module, disable your modules one by one to find out which one causes this.

This can also be caused by UTF-8. If you have your website coded in ASCII and are saving your php files as UTF-8, it can cause this message. If your website and DB are UTF-8, you should be ok with saving php files as UTF-8 though.

Btw, this error message is related to output_buffering on/off in your php.ini. If you have output_buffering set to some cache, the server will allow to send headers with delay (or to modify them shortly after they are sent), and this error will not be tripped. But if you set output_buffering to 0 or not at all, then headers can be sent at only one moment, and if you have some bad code, it will trip this error message.

xjessie007

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Feb 11th, 2009

Re: PHP Warning: Cannot modify header information - headers already sent by (output .

thanks to jenif that worked perfectly few - strange as i had had a site up for sometime and it nevr encountered the problem until recently

Last edited by odalton; Feb 11th, 2009 at 5:59 pm.

odalton

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Jul 3rd, 2009

Re: PHP Warning: Cannot modify header information - headers already sent by (output .

Click to Expand / Collapse Quote originally posted by JeniF ...

try placing this at the top of your page:
<? ob_start(); ?>

then at the bottom of the page place this line of code:

<? ob_flush(); ?>

I Googled on this problem and found your simple solution, JeniF. Because of you, I joined DaniWeb. Thought you should know that even 2 years later your reply is still helping people!

Thanks, JeniF!! And thanks DaniWeb!

John

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