Question

I am using PHP to build a very basic login script. However, the else from the ifelse statement shows by default before the user has even clicked log in.
Before the user has even tried to login they are greeted with this:

Warning: Cannot modify header information - headers already sent by (output started at /home/madhous3/public_html/dev/admin/index.php:12) in /home/madhous3/public_html/dev/admin/login.php on line 13
Sorry, please try again.

How do I stop this? However, if the user enters the details correctly, they are directed to the right page.

Code

index.php

   <?php 
        include("login.php"); 
        ?>
        <h1>Admin Area Login</h1>



        <form method="post" action="login.php">
        Username<input type="text" name="username" />
        Password<input type="text" name="password" />
        <input type="submit" name="log_in" value="Log In" />

        </form>

login.php

<?php 

$username_inputted = $_POST['username'];
$password_inputted = $_POST['password'];


if($username_inputted == 'admin' && $password_inputted == 'password'){

header("location:login_success.php");


}else{
header("location:index.php");
echo "Sorry, please try again."; 
}



?>

Answer 1

Try removing the include(“login.php”) from index.php.

Instead, you should redirect back to index.php from your login.php with a flag specifying that the user entered the wrong information (if they failed the login).

index.php

<?php
    if(isset($_REQUEST['fail'])) {
        echo 'Login failed.';
    }
?>
<h1>Admin Area Login</h1>
<form method="post" action="login.php">
Username<input type="text" name="username" />
Password<input type="text" name="password" />
<input type="submit" name="log_in" value="Log In" />
</form>

login.php

<?php 

$username_inputted = $_POST['username'];
$password_inputted = $_POST['password'];

if($username_inputted == 'admin' && $password_inputted == 'password'){
    header("location:login_success.php");
} else {
    header("location:index.php?fail=1");
}
?>