CHAR,TCHAR,WCHAR 三者的区别与转换

#ifdef   UNICODE     
          typedef   wchar_t   TCHAR;

#else     
          typedef   unsigned   char   TCHAR;

#endif     
typedef   unsigned   char   CHAR;     
typedef   unsigned   wchar_t   WCHAR;

由此可以看出，CHAR实施上就是unsigned char,WCHAR为宽字符，而TCHAR根据是否支持unicode而不同。

在程序使用sizeof(TCAHR)，当默认设置时，这个值是1；当定义UNICODE宏时，这个值是2。

转换函数：
//—————————————————————————–
// Name: DXUtil_ConvertAnsiStringToWide()
// Desc: This is a UNICODE conversion utility to convert a CHAR string into a
//       WCHAR string. cchDestChar defaults -1 which means it 
//       assumes strDest is large enough to store strSource
//—————————————————————————–
VOID DXUtil_ConvertAnsiStringToWide( WCHAR* wstrDestination, const CHAR* strSource, 
                                     int cchDestChar )
{
    if( wstrDestination==NULL || strSource==NULL )
        return;

if( cchDestChar == -1 )
        cchDestChar = strlen(strSource)+1;

MultiByteToWideChar( CP_ACP, 0, strSource, -1, 
                         wstrDestination, cchDestChar-1 );

wstrDestination[cchDestChar-1] = 0;
}

//—————————————————————————–
// Name: DXUtil_ConvertWideStringToAnsi()
// Desc: This is a UNICODE conversion utility to convert a WCHAR string into a
//       CHAR string. cchDestChar defaults -1 which means it 
//       assumes strDest is large enough to store strSource
//—————————————————————————–
VOID DXUtil_ConvertWideStringToAnsi( CHAR* strDestination, const WCHAR* wstrSource, 
                                     int cchDestChar )
{
    if( strDestination==NULL || wstrSource==NULL )
        return;

if( cchDestChar == -1 )
        cchDestChar = wcslen(wstrSource)+1;

WideCharToMultiByte( CP_ACP, 0, wstrSource, -1, strDestination, 
                         cchDestChar-1, NULL, NULL );

strDestination[cchDestChar-1] = 0;
}

//—————————————————————————–
// Name: DXUtil_ConvertGenericStringToAnsi()
// Desc: This is a UNICODE conversion utility to convert a TCHAR string into a
//       CHAR string. cchDestChar defaults -1 which means it 
//       assumes strDest is large enough to store strSource
//—————————————————————————–
VOID DXUtil_ConvertGenericStringToAnsi( CHAR* strDestination, const TCHAR* tstrSource, 
                                        int cchDestChar )
{
    if( strDestination==NULL || tstrSource==NULL )
        return;

#ifdef _UNICODE
    DXUtil_ConvertWideStringToAnsi( strDestination, tstrSource, cchDestChar );
#else
    if( cchDestChar == -1 )
    strcpy( strDestination, tstrSource );
    else
    strncpy( strDestination, tstrSource, cchDestChar );
#endif
}

//—————————————————————————–
// Name: DXUtil_ConvertGenericStringToWide()
// Desc: This is a UNICODE conversion utility to convert a TCHAR string into a
//       WCHAR string. cchDestChar defaults -1 which means it 
//       assumes strDest is large enough to store strSource
//—————————————————————————–
VOID DXUtil_ConvertGenericStringToWide( WCHAR* wstrDestination, const TCHAR* tstrSource, 
                                        int cchDestChar )
{
    if( wstrDestination==NULL || tstrSource==NULL )
        return;

#ifdef _UNICODE
    if( cchDestChar == -1 )
     wcscpy( wstrDestination, tstrSource );
    else
     wcsncpy( wstrDestination, tstrSource, cchDestChar );
#else
    DXUtil_ConvertAnsiStringToWide( wstrDestination, tstrSource, cchDestChar );
#endif
}

//—————————————————————————–
// Name: DXUtil_ConvertAnsiStringToGeneric()
// Desc: This is a UNICODE conversion utility to convert a CHAR string into a
//       TCHAR string. cchDestChar defaults -1 which means it 
//       assumes strDest is large enough to store strSource
//—————————————————————————–
VOID DXUtil_ConvertAnsiStringToGeneric( TCHAR* tstrDestination, const CHAR* strSource, 
                                        int cchDestChar )
{
    if( tstrDestination==NULL || strSource==NULL )
        return;
        
#ifdef _UNICODE
    DXUtil_ConvertAnsiStringToWide( tstrDestination, strSource, cchDestChar );
#else
    if( cchDestChar == -1 )
    strcpy( tstrDestination, strSource );
    else
    strncpy( tstrDestination, strSource, cchDestChar );
#endif
}

//—————————————————————————–
// Name: DXUtil_ConvertAnsiStringToGeneric()
// Desc: This is a UNICODE conversion utility to convert a WCHAR string into a
//       TCHAR string. cchDestChar defaults -1 which means it 
//       assumes strDest is large enough to store strSource
//—————————————————————————–
VOID DXUtil_ConvertWideStringToGeneric( TCHAR* tstrDestination, const WCHAR* wstrSource, 
                                        int cchDestChar )
{
    if( tstrDestination==NULL || wstrSource==NULL )
        return;

#ifdef _UNICODE
    if( cchDestChar == -1 )
     wcscpy( tstrDestination, wstrSource );
    else
     wcsncpy( tstrDestination, wstrSource, cchDestChar );
#else
    DXUtil_ConvertWideStringToAnsi( tstrDestination, wstrSource, cchDestChar );
#endif
}

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