PHP - header('location:profile.php'); not working

when I hit login it keeps saying invalid login information. I want it to go to profile.php
I used header('location:profile.php') I wonder whats wrong? may you guys take a look please, and let me know if I'm missing something or had typos. thanks!

    //database information
$host = "localhost";
$user = "root";
$pass = "";
$db = "test";

//connect to database
mysql_connect($host, $user, $pass);

mysql_select_db($db);

//select table
$sql = "SELECT * FROM users WHERE username='".$username."' AND password='".$password."' LIMIT 1";
    $res = mysql_query($sql);

?>









  

    
NJROTC ADMINS
    

      
You cannot be on this page if you weren't given the login information!  
    

  
  
 
  

  
  

    
















      
        
Username
        
      
      
        
Password
        
      
      
        

          if (isset($_POST['username'])) {
    $username = $_POST['username'];
    $password = $_POST['password'];

    if (mysql_num_rows($res) == 1) {
    echo "You have successfully logged in.";
    exit();
    } else {
    echo "Invalid log in information.";
    exit();
        header ('location:profile.php');
    }
}
?>

        
      
      
        
        
 
      
    
  

Answer

Here is your code:

echo "Invalid log in information.";
exit();
    header ('location:profile.php');

First when you execute an echo the server sends headers to the browser, so you can’t have that before a header call. But past any of that you have an exit(); before the header ('location:profile.php'); call. So that will never execute it. Just do this instead:

// echo "Invalid log in information.";
// exit();
header ('location:profile.php');

Commenting out the echo and exit just in case there is a valid reason for you to have those there. Perhaps for debugging? But if this is in production, those are not needed.