UTF8 Conversion

0
votes

I need to generate a UTF8 string to pass to a 3rd party library and I'm having trouble figuring out the right gymnastics... Also, to make matters worst, I'm stuck using C++ Builder 6 and every example I found talks about using std::string which CBuilder6 evidentially has no support for. I'd like to accomplish this without using STL what so ever.

Here is my code so far that I can't seem to make work.

wchar_t *SS1;
char *SS2;

  SS1 = L"select * from mnemonics;";

  int strsize =  WideCharToMultiByte(CP_UTF8, 0, SS1, wcslen(SS1), NULL, 0, NULL, NULL);

  SS2 = new char[strsize+1];

  WideCharToMultiByte( CP_UTF8, 0, SS1, wcslen(SS1), SS2, strsize, NULL, NULL);

3rd party library chokes when I pass it SS2 as a parameter. Obviously, I'm on a Windows platform using Microsoft's WideCharToMultiByte but eventually I would like to not need this function call as this code must also be compiled on an embedded platform as well under Linux but I'll cross that bridge when I get to it.

For now, I just need to be able to either convert a wchar_t or char to UTF8 encoded string preferably without using any STL. I won't have STL on the embedded platform.

Thanks!

2
utf-8encode

2 Answers

2
votes

Something like that:

extern void someFunctionThatAcceptsUTF8(const char* utf8);

const char* ss1 = "string in system default multibyte encoding";

someFunctionThatAcceptsUTF8( w2u( a2w(ss1) ) ); // that conversion you need:
                                                 // a2w: "ansi" -> widechar string
                                                 // w2u: widechar string -> utf8 string.

You just need to grab and include this file: http://code.google.com/p/tiscript/source/browse/trunk/sdk/include/aux-cvt.h

It should work on Builder just fine.

0
votes

If you're still looking for an answer, here's a simple implementation of a utf8 convertor in C language:

/*
** Transforms a wchar to utf-8, returning a string of converted bytes
*/

void            ft_to_utf8(wchar_t c, unsigned char *buffer)
{
    if (c < (1 << 7))
        *buffer++ = (unsigned char)(c);
    else if (c < (1 << 11))
    {
        *buffer++ = (unsigned char)((c >> 6) | 0xC0);
        *buffer++ = (unsigned char)((c & 0x3F) | 0x80);
    }
    else if (c < (1 << 16))
    {
        *buffer++ = (unsigned char)((c >> 12) | 0xE0);
        *buffer++ = (unsigned char)(((c >> 6) & 0x3F) | 0x80);
        *buffer++ = (unsigned char)((c & 0x3F) | 0x80);
    }
    else if (c < (1 << 21))
    {
        *buffer++ = (unsigned char)((c >> 18) | 0xF0);
        *buffer++ = (unsigned char)(((c >> 12) & 0x3F) | 0x80);
        *buffer++ = (unsigned char)(((c >> 6) & 0x3F) | 0x80);
        *buffer++ = (unsigned char)((c & 0x3F) | 0x80);
    }
    *buffer = '\0';
}