Processing Web Form Input in Latin1 Encoding Error

This section provides a tutorial example demonstrating Web form with default text in Latin1 encoding, but the browser converts it to UTF-8 encoding, which results form data being submitted as UTF-8 encoding.

The next test I did was to try to enter Latin1 characters as Web form input. I wrote a new test PHP script with some interesting features:

<?php 
#- Web-Form-Input-Latin1.php
#- Copyright (c) 2005 HerongYang.com, All Rights Reserved.
#
  print('<html>');
  print('<body>'."\n");

# Default input text
  $input =
    '&#x54;&#xE9;&#x6C;&#xE9;&#x76;&#x69;&#x73;&#x69;&#x6F;&#x6E';
  $input_hex = '54E96CE9766973696F6E'; 

# Form reply determination
  $reply = isset($_REQUEST["Submit"]);

# Process form input data
  if ($reply) {
    if (isset($_REQUEST["Input"])) {
      $input = $_REQUEST["Input"];
    }
  }

# Display form
  print('<form>');
  print('<input type="Text" size="40" maxlength="64"'
   . ' name="Input" value="'.$input.'"/><br/>');
  print('<input type="Submit" name="Submit" value="Submit"/>');
  print('</form>'."\n");

# Display reply
  if ($reply) {
    print('<pre>'."\n");
    print('You have submitted:'."\n");
    print('  Text = '.$input."\n");
    print('  Text in HEX = '.strtoupper(bin2hex($input))."\n");
    print('  Default HEX = '.$input_hex."\n");
    print('</pre>'."\n");
  } 

  print('</body></html>');
?>

After moving this PHP script file to Apache server document directory, I tested it with Internet Explorer (IE) with this URL: http://localhost/Web-Form-Input-Latin1.php. I saw a Web page with a form that has the suggested input text and a submit button.

The suggested Latin1 input characters was displayed correctly, even it was generated by my script as HTML entities.

After clicking the submit button, I saw a returning Web page with the same form and a reply section. However, the French text in hex I received from the form is not the same as the one I created as the default:

Processing Web Form Input in Latin1 Encoding Error
Processing Web Form Input in Latin1 Encoding Error

It looks like my French text started from Latin1 encoding and ended in UTF-8 encoding. For some reason the browser is able to manage this difference.

  Text = Télévision
  Text in HEX = 54C3A96CC3A9766973696F6E
  Default HEX = 54E96CE9766973696F6E

It is interesting to note that the return Web page has a special URL which contains the input text inside the query string. All characters in the input text are ASCII characters except two, which are UTF-8 characters presented as Hex values in the URL.

http://localhost/Web-Form-Input-latin1.php
 ?Input=T%C3%A9l%C3%A9vision&Submit=Submit

See the next tutorial on how to troubleshoot and fix the issue.

Last update: 2019.

Table of Contents

 About This Book

 PHP Installation on Windows Systems

 Integrating PHP with Apache Web Server

 charset="*" - Encodings on Chinese Web Pages

 Chinese Characters in PHP String Literals

 Multibyte String Functions in UTF-8 Encoding

Input Text Data from Web Forms

 Steps and Components Involved

 Processing Web Form Input in ASCII

Processing Web Form Input in Latin1 Encoding Error

 Processing Web Form Input in Latin1

 Entering Latin1 Characters with Alt Keycodes

 Testing Latin1 Alt Keycodes with IE

 Processing Web Form Input in UTF-8

 Outputting Form Default Input Text in UTF-8

 Testing Alt Keycodes with IE on a UTF-8 Web Page

 Input Chinese Text Data from Web Forms

 MySQL - Installation on Windows

 MySQL - Connecting PHP to Database

 MySQL - Character Set and Encoding

 MySQL - Sending Non-ASCII Text to MySQL

 Retrieving Chinese Text from Database to Web Pages

 Input Chinese Text Data to MySQL Database

 Archived Tutorials

 References

 Full Version in PDF/EPUB