Guest book bez SQL

<form method="post">
Nickname: <input type="text" name="nick"><br />
E-mail: <input type="text" name="email"><br />
Subject: <input type="text" name="subject"><br /><br />
<textarea name="message" rows="10" cols="70">
</textarea><br /><br />
<input type="submit" name="sent">
</form>
<?php
// protects against sending the same message by using refresh button
// (header('location') will "unset" the variables)
if ( $_POST['sent'] )
{
header('location: ' . $_SERVER['HTTP_REFERER']);
}

$file = './messages.html';

// write message into the text file
function send_msg($text, $name, $time, $subject='', $email='')
{
 global $file;
 
 $who = 'Message sent by ';
 $when = ' on ';
 $address = 'E-mail: ';
 $title = 'Subject: ';
 
 $subject = ( $subject != '' ) ? $subject : '<i>none</i>';
 $email = ( $email != '' ) ? $email : '<i>none</i>';

 //edits user input
 $text = str_replace("<", "&", $text);
 $text = str_replace(">", "&", $text);
 $text = str_replace("\n", "\n<br />\n", $text);
 
 if(file_exists($file))
 {
  // opens file in the update mode
  $fp = fopen($file, 'a');
 
  // change acording to your needs (font size, colors etc..)
  fputs($fp, $who . '<b>' . $name . '</b>' . $when . $time . '<br />');
  fputs($fp, $address . '<b>' . $email . '</b>' . '<br />');
  fputs($fp, $title . '<b>' .$subject . '</b><br /><br />');
  fputs($fp, $text . '<br /><hr />');
 
  fclose($fp);
 }
 else
 {
  echo 'Couldn\'t load the guestbook';
 }
}
// opens file in the readonly mode
$fp = fopen($file, 'r');
fpassthru($fp);
fclose($fp);
?>

send_msg($_POST['message'], $_POST['nick'], date('d.m.y'), $_POST['subject'], $_POST['email']);

if (!empty($_POST))
{
     send_msg($_POST['message'], $_POST['nick'], date('d.m.y'), $_POST['subject'], $_POST['email']);
}

unset($_POST['message'], $_POST['nick'], $_POST['subject'], $_POST['email']);

send_msg($_POST['message'], $_POST['nick'], date('d.m.y'), $_POST['subject'], $_POST['email']);
     unset($_POST['message'], $_POST['nick'], $_POST['subject'], $_POST['email']);

<?php
$file = "guestbook.txt";
$errMsg = "";
safety($_POST);

if(!isset($_SESSION['lastMsg'])) {
   $_SESSION['lastMsg'] = 0;   
}

//safety(), isValidEmail() z temy pre casto pouzivane skripty

function writeMsg($nick,$email,$subject,$msg) {
   global $file;
   
   $fp = @fopen($file,"a");
   if($fp!==false) {
      $content = date("Y-m-d H:i:s")."\n".$nick."\n".$email."\n".$subject."\n".$msg."\n";
      
      $startTime = microtime();
      do {
         $canWrite = flock($fp, LOCK_EX);
         if(!$canWrite) {
            usleep(round(rand(0, 100)*1000));
         }
      } while(!$canWrite && ((microtime()-$startTime)<1000));
      
      if($canWrite) {
         @fwrite($fp,$content);
         @fclose($fp);
      }
   }
}

function readMsg() {
   global $file;
   
   $content = file($file);
   if(!empty($content)) {
      foreach($content as $i => $data) {
         echo trim($data).'<br>';
         if(($i+1)%5==0) {
            echo '<hr>';
         }
      }
   } else {
      echo 'Ziadne spravy.';
   }
}

if(!empty($_POST)) {
   if(!empty($_POST['nick']) && !empty($_POST['email']) && !empty($_POST['subject']) && !empty($_POST['message'])) {
      if(!isValidEmail($_POST['email'])) {
         $errMsg = "Chybny format emailovej adresy!";   
      } else {
         if(time()-$_SESSION['lastMsg']>10) {
            writeMsg($_POST['nick'],$_POST['email'],$_POST['subject'],$_POST['message']);
            $_SESSION['lastMsg'] = time();
            header("Location: ".$_SERVER['HTTP_REFERER']);
         } else {
            $errMsg = "Klud, klud, si velmi hyperaktivny!";
         }
      }
   } else {
      $errMsg = "Nevyplnil si vsetky povinne udaje!";
   }
}

readMsg();

if(!empty($errMsg)) {
   echo '<p>'.$errMsg.'</p>';
}
?>
<form method="post">
Nick: <input type="text" name="nick">
E-mail: <input type="text" name="email">
Predmet: <input type="text" name="subject">
Sprava: <textarea name="message"></textarea>
<input type="submit" value="Send">
</form>

//safety(), isValidEmail() z temy pre casto pouzivane skripty

foreach($content as $i => $data) {
         echo trim($data).'<br>';
         if(($i+1)%5==0) {
            echo '<hr>';
         }
      }

for($i=count($content)-1; $i>=0; $i--) {
         echo trim($content[$i]).'<br>';
}

            <?
            $smilik_1_edit = array("<img src="smilik.png">")>
            $smilik_1_orig = array(“:D“);                //hodnota premennej $smile1
            foreach ($smilik_1_orig as $smilik_1_edit)      //transformácia premennej $smilik_1_orig na premenú $smilik_1_edit
            {
            echo $smilik_1_edit;
            }
            ?>