Punycode Encoding / Decoding
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Punycode is an encoding standard for representing Unicode characters using only the 7bit us-ascii characters that are permitted in network host names. Punycode is used for internationalized domain names -- i.e. IDN or IDNA (Internationalizing Domain Names in Applications).Punycode is defined in RFC 3492. Converting to/from punycode does not include the "xn--" prefix. The "xn--" prefix is to signify that punycode follows. For example, the string " café.com" is converted to "caf-dma.com" in punycode. The punycode domain name is "xn--caf-dma.com".
Converting an email address to punycode would be as follows. Suppose the email address is "coffee@café.com". The punycode representation is "coffee@xn--caf-dma.com". The RFC 3492 punycode representation of "café.com" is simply "caf-dma.com", but the punycode domain name is "xn--caf-dma.com".
The "xn--" is a constant. It is the same regardless of the domain. For example, the punycode URL representation of "mañana.com" is "xn--maana-pta.com".
Chilkat Classic ASP Downloads
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
</head>
<body>
<%
success = 0
set sb = Server.CreateObject("Chilkat.StringBuilder")
' Load the string "café" from a utf-8 text file.
success = sb.LoadFile("qa_data/txt/cafe.txt","utf-8")
success = sb.PunyEncode()
Response.Write "<pre>" & Server.HTMLEncode( sb.GetAsString()) & "</pre>"
success = sb.PunyDecode()
Response.Write "<pre>" & Server.HTMLEncode( sb.GetAsString()) & "</pre>"
' The output is:
'
' caf-dma
' café
%>
</body>
</html>