ANSI to UNICODE on windows using STL strings
cpp
// convert a path from ANSI to UNICODE on windows using std::strings
// useful for converting a boost::filesystem::path into a wpath, until those APIs get merged
std::wstring convertStringToWString( std::string in )
{
    if (in.length() == 0 )
    {
        return std::wstring();
    }
 
    UINT wStringLength = MultiByteToWideChar(CP_ACP, 0, in.c_str(), -1, NULL, 0);
    if (wStringLength==0)
    {
        return std::wstring();
    }
 
    LPWSTR widestr = new WCHAR[wStringLength];
    wStringLength = MultiByteToWideChar( CP_ACP, 0, in.c_str(), -1, widestr, wStringLength );
    if ( wStringLength ==0 )     
    {
        delete[] widestr;
        return std::wstring();
    }
 
    std::wstring returnVal = std::wstring( widestr );
    delete[] widestr;
 
    return returnVal;
}