$Id: encoding.txt 1759 2008-01-28 22:56:08Z mjs $

HOW TO ENCODE/DECODE VARIOUS STRINGS

HTML (NAMED) ENTITIES

PHP

  htmlentities($s, ENT_QUOTES, $input_charset)
  html_entity_decode($s, ENT_QUOTES, $output_charset)

XML (NUMERIC) ENTITIES

PHP

?

If you can get away with UTF-8, though, you can use
html_entity_decode() as above.

URI

Perl

  use URI::Escape;
  
  uri_escape($s);
  uri_unescape($s);
  
PHP

  urlencode($s);
  urldecode($s);
  
Javascript

  encodeURI(s); // does not encode question mark (?)
  decodeURI(s); // does not encode question mark (?)

  encodeURIComponent(s); // encodes question mark (?)
  decodeURIComponent(s); // encodes question mark (?)

  escape(s);   // deprecated
  unescape(s); // deprecated

MIME/EMAIL HEADERS (RFC 2047)

Perl

  use MIME::WordDecoder;
  
  unmime($s); // decodes to iso-8859
  
Python http://docs.python.org/lib/module-email.header.html

  python
  
  >>> from email.header import decode_header
  >>> decode_header('=?iso-8859-1?q?p=F6stal?=')
  [('p\xf6stal', 'iso-8859-1')]

PHP

  iconv_mime_encode()
  iconv_mime_decode()

MIME BODY

PUNYCODE (DOMAIN NAMES)