Question

Any idea why this wont print the errors?

// Validate the email
if (preg_match($regex, $email))  
        $errors[] = "Invalid email address";

    // ... and the password
    if (strlen($password) < 4)
        $errors[] = "Password is too short";

    // No errors?   
    if (empty($errors))
    {
        // insert into db

    }

// If there were any errors, show them
if (!empty($errors))
{
    $errors = array();
    foreach ($errors as $error)
    echo '<li>'.$error.'</li>';
}

Answer 1

you are overwriting the array before output.

 $errors = array();  // Creates an empty array
 foreach ($errors as $error)  // Won't do anything

remove $errors = array() and it should work.

It would be cleaner by the way to initialize $errors = array() in the very beginning of the script, and then check for count($errors) > 0 instead of empty:

// No errors?   
if (count($errors) == 0)
{
 // insert into db

}

// If there were any errors, show them
else
{
    $errors = array();
    foreach ($errors as $error)
    echo '<li>'.$error.'</li>';
}

that way, you will avoid notices about $error not being set.