PHP if语句不显示HTML

Question

So I'm checking if a user is logged in, and if so I'll remove the signup forms. So I thought I'd do it with if else statements. So here's my code

<?php if($_SESSION['loggedin'] === false): ?>
<h1>Sign Up</h1>
<?php elseif($_SESSION['loggedin'] === true):?>
<h1>Welcome</h1>
<?php endif;?>

For some reason all I get is a blank page. I'm using

error_reporting(E_ALL);
ini_set('display_errors', '1');

To display errors, but I'm not getting anything. On another page when doing a var_dump on $_SESSION['loggedin' I get bool(true), so I know that I'm logged in and expect Welcome. I feel like its a syntax error. Any ideas?

Answer 1

If you tail your server logs (e.g. tail -F logs/php_error.log) you'll probably see something like:

PHP Notice: Undefined variable: _SESSION

Try changing the code to:

if (isset( $_SESSION['loggedin'] ) && $_SESSION['loggedin'] == true )
{
  echo 'Welcome';
} else {
  echo 'Sign up';
}

Personally I'd also recommend changing your sign out logic to use unset($_SESSION) that way you only have to check for:

if (isset( $_SESSION['loggedin'] ) ){
  echo 'Welcome';
} else {
  echo 'Sign up';
}