Re: MODIFIED: Copying a CString to a std::string via TCHAR

Giovanni Dicanio wrote:


BTW: in case that conversion would be useful to the OP, here is some
code I wrote for that purpose (it is based on ATL and STL std::string
and std::vector classes, so can be used also in Win32 non-MFC projects):

<code>

#include <vector>
#include <string>

//----------------------------------------------------------------------------
// NAME: ConvertUTF16ToUTF8
// DESC: Converts Unicode UTF-16 (Windows default) text to Unicode UTF-8
//----------------------------------------------------------------------------
std::string ConvertUTF16ToUTF8( IN const wchar_t * utf16 )
{
     //
     // Check input pointer
     //
     ATLASSERT( utf16 != NULL );
     if ( utf16 == NULL )
         AtlThrow( E_POINTER );

     //
     // Handle special case of empty string
     //
     if ( *utf16 == L'\0' )
     {
         return "";
     }

     //
     // Consider wchar_t's count corresponding to total string length,
     // including end-of-string (L'\0') character.
     //
     const int utf16Length = wcslen( utf16 ) + 1;

     //
     // Get size of destination UTF-8 buffer, in chars (= bytes)
     //
     int utf8Size = ::WideCharToMultiByte(
         CP_UTF8, // convert to UTF-8
         0, // default flags
         utf16, // source UTF-16 string
         utf16Length, // total source string length, in wchar_t's,
         // including end-of-string \0
         NULL, // unused - no conversion required in this step
         0, // request buffer size
         NULL, NULL // unused
         );
     ATLASSERT( utf8Size != 0 );
     if ( utf8Size == 0 )
     {
         AtlThrowLastWin32();
     }

     //
     // Allocate destination buffer for UTF-8 string
     //
     std::vector< char > utf8Buffer( utf8Size );

     //
     // Do the conversion from UTF-16 to UTF-8
     //
     int result = ::WideCharToMultiByte(
         CP_UTF8, // convert to UTF-8
         0, // default flags
         utf16, // source UTF-16 string
         utf16Length, // total source string length, in wchar_t's,
         // including end-of-string \0
         &utf8Buffer[0], // destination buffer
         utf8Size, // destination buffer size, in bytes
         NULL, NULL // unused
         );
     ATLASSERT( result != 0 );
     if ( result == 0 )
     {
         AtlThrowLastWin32();
     }

     //
     // Build UTF-8 string from conversion buffer
     //
     return std::string( &utf8Buffer[0] );
}

</code>

In case there is a need to convert from a Unicode UTF-16 CString (in
Unicode build, or when explicit CStringW is used) to Unicode UTF-8 and
store the result in std::string, this code should work:

   // Unicode build or use CStringW
   CString str;
   ... assing str...

   // Convert from UTF-16 'str' to UTF-8
   // (non-losing conversion)
   std::string utf8String = ConvertUTF16ToUTF8( str );

HTH,
Giovanni