zip code to city in php using geodata

<?


function get_zip_info($zip) { //Function to retrieve the contents of a webpage and put it into $pgdata
  $pgdata =""; //initialize $pgdata
  $fd = fopen("http://zipinfo.com/cgi-local/zipsrch.exe?zip=$zip","r"); //open the url based on the user input and put the data into $fd
  while(!feof($fd)) {//while loop to keep reading data into $pgdata till its all gone
    $pgdata .= fread($fd, 1024); //read 1024 bytes at a time
  }
  fclose($fd); //close the connection
  if (preg_match("/is not currently assigned/", $pgdata)) {
    $city = "N/A";
        $state = "N/A";
  }
  else {

      $citystart = strpos($pgdata, "Code</th></tr><tr><td align=center>");
    $citystart = $citystart + 35;
    $pgdata = substr($pgdata, $citystart);
    $cityend = strpos($pgdata, "</font></td><td align=center>");
    $city = substr($pgdata, 0, $cityend);
 
    $statestart = strpos($pgdata, "</font></td><td align=center>");
    $statestart = $statestart + 29;
    $pgdata = substr($pgdata, $statestart);
    $stateend = strpos($pgdata, "</font></td><td align=center>");
    $state = substr($pgdata, 0, $stateend);
    }
     $zipinfo[zip] = $zip;
     $zipinfo[city] = $city;
     $zipinfo[state] = $state;
     return $zipinfo;
}
if ( $_POST['zip'] == "" ) {
  ?>
    <form action="<? echo $_SERVER['PHP_SELF']; ?>" method="post">
    <input type="text" name="zip" >
    <input type="submit" value="Find Zip Info">
    </form>
  <?
}
else {
  $works = get_zip_info($_POST['zip']);
 
  echo "Zip Code: ".$works[zip]."<br>City: ".$works[city]."<br>State: ".$works[state];
}
?>