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Introduction

The document discusses the use of UNICODE to produce international (I18N) applications. This type of application is necessary when using 16 bit character sets such as those used in Chinese languages.

Getting started

To take advantage of the MFC and C run-time support for Unicode, you need to:

Define _UNICODE

Under C/C++ tab in Project settings, Category: General. Remove _MBCS and add _UNICODE to the list of Preprocessor Definitions.

Specify entry point

In the Output category of the Link tab in the Project Settings dialog box, set the Entry Point Symbol to wWinMainCRTStartup.

Install correct librarys

The default installtion of VC++ does not install the unicode librarys. To get these librarys to must run the Visual Studio setup and drill down into VC installed components to install the correct libraries.

• Microsoft Visual C++
• VC++ MFC and Template Libraries
• MS Foundation Class Libraries
• (** Get the lot **)

Use ¢Îortable¢Îrun-time functions and types

Use the proper C run-time functions for Unicode string handling. You can use the wcs family of functions, but you SHOULD use the fully ¢Îortable¢Î (internationally enabled) _TCHAR macros. These macros are all prefixed with _tcs; they substitute, one for one, for the str family of functions.

Handle literal strings properly

The Visual C++ compiler interprets a literal string coded as L"this is a literal string" to mean a string of Unicode characters. You can use the same prefix for literal characters. Use the _T macro to code literal strings generically, so they compile as Unicode strings under Unicode or as ANSI strings (including MBCS) without Unicode. For example, instead of:
    pWnd->SetWindowText( ¢Îello¢Î);
use:
    pWnd->SetWindowText( _T(¢Îello¢Î );
With _UNICODE defined, _T translates the literal string to the L-prefixed form; otherwise, _T translates the string without the L prefix.
Tip The _T macro is identical to the _TEXT macro.

Displaying chinese charactors

To display chinese charactors requires the correct font to be installed. Two methods are to be used depending on what operating system you are using.

Running Chinese WinNT

Under Chinese NT you simply create a UNICODE application is display a character such as;

WCHAR szOut[255];
szOut[0] = 0x58C6;
szOut[1] = 0x6A4E;
szOut[2] = 0x6FB8;
szOut[3] = 0x5673;
szOut[4] = NULL;
SetDlgItemText( IDC_EDIT, szOut ); 

Running non Chinese WinNT

Under this operating system it is necessary to specifiy a font to display the chararctors as follows;

//Get the default font height and Define new font
CFont* pfont = GetDlgItem( IDC_EDIT_IN )->GetFont();
LOGFONT LogFont;pfont->GetLogFont( &LogFont );
bool b = m_fontChinese.CreatePointFont(
    LogFont.lfHeight*(10),  
    _T("MingLiU") );
GetDlgItem( IDC_EDIT )->SetFont( &m_fontChinese );
//^^^^ Above code in InitDialog^^^^^
    
//Some where in the application..
WCHAR szOut[255];
szOut[0] = 0x58C6;
szOut[1] = 0x6A4E;
szOut[2] = 0x6FB8;
szOut[3] = 0x5673;
szOut[4] = NULL;
SetDlgItemText( IDC_EDIT, szOut );

Using conversion Macros

When using WCHAR or TCHAR and char strings together in the same application it is often necessary to convert between these types. This is often the case when data comes from a socket connection or an ASCI file.

USES_CONVERSION;
char szSmall[] = "small string";
TCHAR* szWide = A2T( szSmall );

The above code takes an ANSI string and converts it into a char if compiled with _MBCS and into a wchar if compiled with _UNICODE. The USES_CONVERSIONS macro ensures the created string is cleaned up is necessary.

Handy referances

The following articles have some good information on this topic