Registrace uzivatele

<?php
if(isset($_POST["odeslat"])){
  require "./fce.php";
  $username = $_POST["username"];
  $pw = "/\A".$_POST["heslo"]."\z/";
  $pw2 = $_POST["heslo2"];
  $strFile = file_get_contents("login.txt");
  if(check($strFile, $username, ""))
    echo "Uživatel již existuje!<br />\n";
  else{
    if(preg_match($pw, $pw2)==0){
      echo "Hesla nejsou stejná!<br />\n";
    }else{
      file_put_contents("login.txt", $username.":".$pw2."\n", FILE_APPEND);
    }
  }
}
?>
<form action='reg.php' method='POST'>
<table>
<tr><td>Uživatelské jméno:</td><td><input type='text' name='username' /></td></tr>
<tr><td>Heslo:</td><td><input type='password' name='heslo' /></td></tr>
<tr><td>Heslo znovu:</td><td><input type='password' name='heslo2' /></td></tr>
</table>
<input type='submit' name='odeslat' value='odeslat' />
</form>