Cannot modify header information - headers already sent by

[suttercain]

Hi guys,

 

this is straight from a book I am working from:

<?php session_start(); ?>
<?php
require ('get_connected.php');
if (isset($_POST['user']) && isset($_POST['password'])) {
    $sql = "SELECT * FROM users";
    if ($result = mysql_query($sql)) {
      if (mysql_num_rows($result)) {
        $row = mysql_fetch_assoc($result);
		if ($user == $row['user'] && $password == $row['password'])	{
			$_SESSION['Approved'] = 1;
			} else {
			$_SESSION['Approved'] = 0;
			}
		header("Location: admin_canada.php");
	}
      }
    }

if (isset($_GET['logout'])) {
session_destroy();
header("Location: canada_login.php");
}
?>

 

Is this code incorrect? Becuase I am getting this error:

Warning: Cannot modify header information - headers already sent by (output started at C:\wamp\www\ARB\pio\get_connected.php:7) in C:\wamp\www\ARB\pio\logged_in.php on line 15

[MadTechie]

looking at the error do you want to post the

code for get_connected.php then ?

[AndyB]

get_connected.php probably has some output to the browser. Even 'white space' counts as output.

[boo_lolly]

he doesn't have to post the included file. basically you've just printed something out to the browser before you called the header function. you can't do that.

http://www.phpfreaks.com/forums/index.php/topic,37442.0.html

 

the alternative would be to replace your header() with a meta-redirect:

http://webdesign.about.com/od/metataglibraries/a/aa080300a.htm

[DrDre]

It all depends on what your intending to do with that include. Is it a form to login?

 

If so, you can use output buffering to make your current file work without errors, but there is a better way to do it than what your doing if that is whats in get_connected.php

 

use this as a last resort to make it work:

 

<?php 
session_start();
ob_start();
require ('get_connected.php');
$data=ob_get_contents();
ob_end_clean();
if (isset($_POST['user']) && isset($_POST['password'])) {
    $sql = "SELECT * FROM users";
    if ($result = mysql_query($sql)) {
      if (mysql_num_rows($result)) {
        $row = mysql_fetch_assoc($result);
		if ($user == $row['user'] && $password == $row['password'])	{
			$_SESSION['Approved'] = 1;
			} else {
			$_SESSION['Approved'] = 0;
			}
		header("Location: admin_canada.php");
	}
      }
    }

if (isset($_GET['logout'])) {
session_destroy();
header("Location: canada_login.php");
}
echo $data;
?>

[boo_lolly]

docta dre is right about using output buffering. but i think that uses more resources than necessary and can cause problems to arise elsewhere in the future. meta-redirect does the exact same thing as header() for what you want to do.