Advanced Globalization Topics with Microsoft 'NET Framework

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Advanced Globalization Topics with Microsoft .NET
Framework

• François Liger
• Program Manager
• Microsoft Corporation
• francl_at_microsoft.com

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Summary

• Dealing with Cultures
• Handling strings
• Interoperability
• Dealing with encodings

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Cultures

• The .NET Framework uses cultures
• Provide cultural preferences
• Replaces and extends the LCID in Win32
• CultureInfo class
• RFC 1766 derived hierarchy
• Three types of cultures
• Two roles
• CurrentCulture globalization role
• Date, and number formatting
• String comparison and casing
• CurrentUICulture localization role
• Resource selection for user interface

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Culture types and roles

• Invariant culture
• culture-invariant default
• Neutral culture
• Based on language
• Resource only
• No formatting
• CurrentUICulture only
• Specific culture
• Based on language region
• Resource Formatting specifics
• CurrentCulture CurrentUICulture

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CultureInfo
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Using CultureInfo for globalization

• CurrentCulture
• Set by default (based on GetUserDefaultLCID)
• Culture-sensitive APIs (except resources) use
  this culture by default

MyString "this is a string" MyCaps
MyString.Upper()
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Setting culture explicitly

• Useful for server scenarios
• Examples
• Thread.CurrentThread.CurrentUICulture new
  CultureInfo(ja)
• Thread.CurrentThread.CurrentCulture new
  CultureInfo(ja-JP)
• Thread.CurrentThread.CurrentCulture
  CultureInfo.CreateSpecificCulture(Request.UserLang
  uages(0))

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Using CultureInfo for globalization

• Explicitly indicating culture in API
• Use when several cultures need to be handled at
  once

// convert a string formatted using
hi-IN CultureInfo HindiIndia new
CultureInfo(hi-IN) CultureInfo FrenchFrance
new CultureInfo(fr-FR) string s
12,34,567.00 int n int.Parse(s,
NumberStyles.AllowDecimalPoint
NumberStyles.AllowThousands, HindiIndia) Console.
WriteLine(n.ToString("n", FrenchFrance))
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Using CultureInfo for globalization

• CultureInfo.InvariantCulture
• For UI, prefer culture-sensitive formatting
• However, for culture-neutral operations (e.g.
  database storage, back end processing, system
  object comparisons) you may need stable,
  culture-unrelated format, such as
• ,.
• dd MMMM yyyy HHmmss GMT
• international currency symbol

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Using culture for localization

• Use built-in fallback
• Only set culture explicitly if really required

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Extending culture

• Custom Culture sample

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Handling strings

• Combining characters
• Supplemental characters (Surrogate pairs)
• Recommendations

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Combining characters

• Some characters can be expressed
• As pre-composed characters
• As base character combining character(s)

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Combining Characters

• Supported through the StringInfo class
• StringInfo.ParseCombiningCharacters()
• Parses a string into text elements.
• A text element is a unit of text that is
  displayed as a single character.
• StringInfo.GetTextEnumerator
• The StringInfo class provides access to the
  TextEnumerator class via the StringInfo.GetTextEnu
  merator method.

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Supplemental Characters

• Over 1 million additional characters
• Why should you care?
• Used for East Asian Languages
• Used in Japan, Taiwan
• Used for converting to/from GB18030
• Used for other scripts too
• Surrogate pairs
• High surrogate Low surrogate
• A surrogate pair points to a supplemental
  character
• Strictly-defined ranges for surrogate characters
• Easier than DBCS (e.g. to walk strings)
• Still requires some effort

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Supplemental Characters
Basic Multilingual Plane
Supplemental characters
16-bit
21-bit
High surrogate
Low surrogate
UD840
UDC58
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Supplemental Characters

• Supported through the StringInfo class
• StringInfo.ParseCombiningCharacters()
• Parses a string into text elements.
• A text element is a unit of text that is
  displayed as a single character.
• StringInfo.GetTextEnumerator
• The StringInfo class provides access to the
  TextEnumerator class via the StringInfo.GetTextEnu
  merator method.
• Encoding classes support supplemental characters
  when appropriate (e.g. GB18030)

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Surrogate pairs combining characters

• Demo

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Comparing strings

• Which API to choose?
• Demo

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String handling recommendations

• Deal with strings whenever possible
• Only deal with individual characters if there is
  no other choice
• Rely on the StringInfo methods to handle
  surrogates and combining characters
• StringInfoParseCombiningCharacters
• StringInfoGetTextEnumerator

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Interoperability with Win32

• Internationalization APIs available in managed
  code
• Hower sometimes, the need for a native API occurs
• CultureInfo exposes an LCID for interop
• Watch for String type though

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Interoperability with Win32

• Demo

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Encodings

• Encoding class
• Provides base class for all other encodings
• Support for codepage based encodings
• E.g. support for GB18030 through this class
• Unicode (UTF-16 and UTF-8) encodings classes
• UnicodeEncoding
• UTF8Encoding

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Encodings

• Demo

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Questions and Links

• Questions?
• Useful Links
• http//www.microsoft.com
• http//www.gotdotnet.com
• http//www.asp.net