Upravovanie txt suboru pomocou php

<?php
if (!empty($_POST["text"])) {
  file_put_contents('./data.txt', $_POST["text"]);
}
?>

<?php
if (!empty($_POST["text"])) {
  $file = fopen('./data.txt', 'w');
  fwrite($file, $_POST["text"]);
  fclose($file);
}
?>

<?php
$loadcontent = "data.dat";
if($save_file)
  {
    $savecontent = stripslashes($savecontent);
    $fp = @fopen($loadcontent, "w");
    if ($fp)
      {
        fwrite($fp, $savecontent);
        fclose($fp);
      }
  }
$fp = @fopen($loadcontent, "r");
$loadcontent = @fread($fp, filesize($loadcontent));
$loadcontent = htmlspecialchars($loadcontent);
fclose($fp);
?>
<form method=post action="edit.php">
  <input type="text" class="post" name="savecontent" size="3" value="<?=$loadcontent?>">
  <input type="submit" name="save_file" value="Uložiť">
</form>