IdnMapping Class
Supports the use of non-ASCII characters for Internet domain names. This class cannot be inherited.
Assembly: mscorlib (in mscorlib.dll)
The IdnMapping type exposes the following members.
| Name | Description | |
|---|---|---|
![]() | AllowUnassigned | Gets or sets a value indicating whether unassigned Unicode code points are used in operations performed by members of the current IdnMapping object. |
![]() | UseStd3AsciiRules | Gets or sets a value indicating whether standard or nonstandard naming conventions are used in operations performed by members of the current IdnMapping object. |
| Name | Description | |
|---|---|---|
![]() | Equals | Indicates whether a specified object and this IdnMapping object are equal. (Overrides Object::Equals(Object).) |
![]() | Finalize | Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.) |
![]() | GetAscii(String) | Encodes a string of one or more domain name labels that consist of Unicode characters to a string of Unicode characters in the US-ASCII character range. |
![]() | GetAscii(String, Int32) | Encodes a substring of one or more domain name labels that consist of Unicode characters to a string of Unicode characters in the US-ASCII character range. |
![]() | GetAscii(String, Int32, Int32) | Encodes a substring of one or more domain name labels that consist of Unicode characters to a string of Unicode characters in the US-ASCII character range. The string is formatted according to the Internationalizing Domain Names in Applications (IDNA) standard. |
![]() | GetHashCode | Returns a hash code for this IdnMapping object. (Overrides Object::GetHashCode().) |
![]() | GetType | Gets the Type of the current instance. (Inherited from Object.) |
![]() | GetUnicode(String) | Decodes a string of one or more domain name labels encoded according to the Internationalizing Domain Names in Applications (IDNA) standard to a string of Unicode characters. |
![]() | GetUnicode(String, Int32) | Decodes a substring of one or more domain name labels encoded according to the Internationalizing Domain Names in Applications (IDNA) standard to a string of Unicode characters. |
![]() | GetUnicode(String, Int32, Int32) | Decodes a substring of one or more domain name labels encoded according to the Internationalizing Domain Names in Applications (IDNA) standard to a string of Unicode characters. |
![]() | MemberwiseClone | Creates a shallow copy of the current Object. (Inherited from Object.) |
![]() | ToString | Returns a string that represents the current object. (Inherited from Object.) |
An Internet domain name consists of one or more parts, called domain name labels, separated by label separators. For example, the domain name "www.microsoft.com" consists of the labels, "www", "microsoft", and "com" separated by periods.
The Internationalizing Domain Names in Applications (IDNA) mechanism maps an internationalized domain name that contains Unicode characters outside the US-ASCII character range to an IDNA domain name that consists of Unicode characters solely in the displayable US-ASCII character range. The IDNA mechanism is used to convert only domain names, not data transmitted over the Internet.
The IdnMapping class embodies and extends the IDNA mechanism. The GetAscii method normalizes a domain name, converts the normalized name to a representation that consists of displayable Unicode characters in the US-ASCII code point range (U+0020 to U+007E), and prepends an ASCII Compatible Encoding prefix ("xn--") to each label.
The label separator characters IDEOGRAPHIC FULL STOP (U+3002), FULLWIDTH FULL STOP (U+FF0E), and HALFWIDTH IDEOGRAPHIC FULL STOP (U+FF61) are converted to the label separator FULL STOP (period, U+002E).
For more information, see the RFC 3490 standard, "Internationalizing Domain Names in Applications," at Request for Comments (RFC). Standards bodies are working on updates to the IDNA standard; see the Internet Engineering Task Force working group (http://tools.ietf.org/wg/idnabis/). There will probably eventually be a follow up to the current IDN standards.
The following code example uses the GetAscii(String, Int32, Int32) method to convert a domain name to a domain name that complies with the IDNA standard. The GetUnicode(String, Int32, Int32) method then converts the standardized domain name back into the original domain name, except that the original label separators are replaced with the standard label separator.
Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.


