if(isset($_POST['kirit'])){
$matn = $_POST['matn'];

$all = strlen($matn);
echo''.$all.' belgi';
}


echo'<form name="form" action="" method="POST">
Matnni kiriting: <br>
<textarea name="matn">Matn</textarea><br>
<input name="kirit" type="submit" value="OK">
</form>';