PHP read file else another file

Question

I have problem here, if I start this script, server returns no value, I know this script isn't ideal for the server optimization, but Im already without any ideas. I need solution, If I choose Czech or English from my option, server returns correct values. Folders are in same address book. Will be glad for your time and help

<select name="example">
<option value="czech" name="czlang" selected="selected">Czech</option>
<option value="eng" name="enlang">English</option>
</select>

<?php
$czfolder = fopen("cz_data.txt", "r");
$enfolder = fopen("en_data.txt", "r");

if(isset($_GET["czlang"])) {
    echo(fread($czfolder, "100"));
      fclose($czfolder); }

if(isset($_GET["enlang"])) {
    echo(fread($enfolder, "100"));
      fclose($enfolder);  
        } 
?>

Answer 1

<?php
// suggestion: always start with php.  Wait to output 
// anything until you are done processing everything.

// avoid non-existent key on inital run. Take action only on submission.
if(array_key_exists('example', $_GET)) {

  // using a switch statement is purely a matter of personal preference.
  // act on form input, then optionally die before printing form
  $choice = $_GET['example'];
  switch ($choice) {
    case 'czlang':
      print "show Czech...";
      //$czfolder = fopen("cz_data.txt", "r");
      //echo(fread($czfolder, "100"));
      //fclose($czfolder); }
      die;

    case 'enlang':
      print "show English...";
      //$enfolder = fopen("en_data.txt", "r");
      //echo(fread($enfolder, "100"));
      //fclose($enfolder);  
      die;
  }

}

// processing done; output html

?>
<h1>Choose Language</h1>
<form method="get">
  <select name="example">
    <option value="czlang" selected="selected">Czech</option>
    <option value="enlang">English</option>
  </select>
  <input type="submit" value="Display" />
</form>