<form name="web_form" id="web_form" method="post" action="process-form-data.php">
        <p><label>Name: </label><input type="text" name="name" id="name" /></p>
        <p><label>Email: </label><input type="text" name="email" id="email" /></p>
        <p><label>Phone: </label><input type="text" name="phon" id="email" /></p>
        <p><label>Address: </label><input type="text" name="add" id="email" /></p>
        <p><input type="submit" name="1" id="s1" value="Submit" /></p>
</form>

php code :

<?php
$name = $_POST['name'];
$email = $_POST['email'];
$phon = $_POST['phon'];
$add= $_POST['add'];
$fp = fopen("mailing.txt", "a");
$savestring = $name . "," . $email .",".$phon."."$add. "n";
fwrite($fp, $savestring);
fclose($fp);
echo "<h1>You data has been saved in a text file!</h1>";
?>
I have a text file mailing.txt
with predefined format
like :
Name    Email   Phone   Address

when I will submit the form.
the data must come (append) in each mentioned below column please help .