<?php
    if(isset($_POST['submit']))
    {
        $username=htmlspecialchars(trim($_POST['username']));
        $password=htmlspecialchars(trim($_POST['password']));
        $repeatpassword=htmlspecialchars(trim($_POST['repeatpassword']));
        
        if($username&&$password&&$repeatpassword)
        {
            if(strlen($username)>=4)
            {
                if(strlen($password)>=4)
                {
                    if(strlen($password==$repeatpassword))
                    {
                        mysql_connect('localhost','root','');
                        mysql_select_db('phpmembre');
                        
                        $query=mysql_query("INSERT INTO users VALUES('','$username','$password')");
                    }else echo "pa ident";
                }else echo "Mot de passe trop cour";
            }else echo "Nom trop cour";
        }else echo "Remplit Tout les champs!";
?>    
    <title>inscription</title>
    <h1>Insciription</h1>
<form method="POST" action="register.php">
    <p>username</p>
    <input type="text" name="username">
    <p>password</p>
    <input type="password" name="password">
    <p>rèpeat password</p>
    <input type="password" name="repeatpassword"><br>
    <input type="submit" value="Inscription">
</form>