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<?include_once "sharedmemory.class.php";
 
 $s = new SharedMemory(54645645);                    //create instance of shared memory object
 $history = $s->Get();                        //read contents
 
 $username = isset($_POST["username"])?$_POST["username"]:"Anonymous";
 
 //add user message to history and write result back to shared memory
 if (isset($_POST["chat"]) && $_POST["chat"] != "") {
 $history .= sprintf("%s says: %s", $username, $_POST["chat"].chr(13));
 //strip oldest message if history exceeds 200 lines
 if (substr_count($history, chr(13)) > 200) {
 $history = substr($history, 1+strpos($history, chr(13)));
 }
 $s->Set($history);
 }
 
 //render history to textarea
 echo "<textarea rows=30 cols=80>$history</textarea>";
 
 //render user input controls
 echo "<form method='POST'>";
 echo "  <input type='text' size=20 name='username' value='$username'>";
 echo "  <input type='text' size=40 name='chat'>";
 echo "  <input type='submit' value='Send/Refresh'>";
 echo "</form>";
 ?>
 
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