Matching Part of a String from File Read

Question

I am asking a user to enter a name and email address. When the form is submitted, a file is read and I compare this to the users name and email to see if they match part of the string.

$fname=$_POST['fname'];
//validate name field
function namecheck ($fname) 
{
    $regexp ="/^[A-Za-z]+$/";
 if (! preg_match($regexp, $fname)) 
 {
         return false;
 }
    return true;
}

$message = "name is :" . $fname. "\n";
if (isset($_POST['submit'])) {
if (!namecheck ($fname))
{
    echo'<script type="text/javascript">alert("Enter your name.")</script>';
    return false;
}
else
    {

  if ( ! file_exists("users.txt"))
         {
         echo'<script type="text/javascript">alert("file does not exist")</script>';
         }
    else
     {
        $userStr = readfile("users.txt");
     if (preg_match($userStr, $fname))
         {

        $fp = fopen ("users.txt", "a");
        fwrite($fp, $message);
        fclose($fp);
         }
    }

}

My question here, is: Will this check to see if the $fname is a part of the users.txt file?

Answer 1

Just change this line :

if (preg_match($userStr, $fname))

by this one:

if (preg_match("/$fname/", $userStr))

Your regex to check the name is very restrictive, names like O'Connors or Jean-François won't pass .