Username & Password Validation

<?php
// Declare some stuff.
$username = "";
$password = "";

// This is not required, but is encouraged to declare all variables.
$errors = array();

// Username stuff.
if(strlen($username) == 0)
{
    $errors[] = "Where is your username!?";
}
elseif(strlen($username) < 2 || strlen($username) > 32)
{
    $errors[] = "Yur username doesn't meet the requirements! It must not fall below 2 and must not exceed 32 characters.";
}

// Password stuff.
// The second check is pointless, however, it's just an example of what you can do.
if(strlen($password) <= 0)
{
    $errors[] = "Where is duh password!?";
}
elseif(hash("sha512", $password) !== hash("sha512", $password))
{
    $errors[] = "Why don't duh passwords match!?";
}

// Count the errors, if their is >= 1, list them here.
if(count($errors) >= 1)
{
    echo "You have the following problems..";
    echo "<ul>";
    foreach($errors as $error)
    {
        echo "<li>" . $error . "</li>";
    }
    echo "</ul>";
}
else
{
    echo "Login has been accepted.";
}
?>