c++ converting string to wstring

gistfile1.cpp

static int strConv(const string &src, wstring &dst) 
{   
    iconv_t cd = iconv_open("UCS-4-INTERNAL", "UTF-8");
    if (cd == (iconv_t)-1)
        return -1;
    
    size_t src_length = strlen(src.c_str());
    int wlen = (int)src_length/3;    
    size_t buf_length = src_length + wlen;
    
    char src_buf[src_length];
    strcpy(src_buf, src.c_str());
    char *buf = new char [buf_length];
    char *inptr = src_buf;
    char *outptr = buf;
    if (iconv(cd, &inptr, &src_length, &outptr, &buf_length) == -1) 
    {
        if (buf!=NULL)
            delete [] buf;
        return -1;
    }
    iconv_close(cd);
    
    dst = wstring(reinterpret_cast<wchar_t*>(buf));
    dst = dst.substr(0, wlen);
    
    if (buf!=NULL)
        delete [] buf;
    
    return wlen;    
}