还是把这个小工具最主要的两个转换函数的源码贴出来吧：

/**
 * GBK->UNICODE
 */
void CGBK2UnicodeDlg::OnConvertText()
{
 //我的视图      鎴戠殑瑙嗗浘
 UpdateData(TRUE);

 int wc = WideCharToMultiByte(CP_UTF8,0,m_txt_input.AllocSysString(),m_txt_input.GetLength(),0,0,NULL,NULL);

 TCHAR* sUnicode = new TCHAR[wc+1];
 sUnicode[wc] = 0;

 WideCharToMultiByte(CP_UTF8,0,m_txt_input.AllocSysString(),m_txt_input.GetLength(),sUnicode,wc,NULL,NULL);
 SetDlgItemText(IDC_UNICODE_TEXT, sUnicode);

 if(sUnicode)
  delete[] sUnicode;

 GetDlgItem(IDC_GBK_TEXT)->SetFocus();
}

/**
 * UNICODE->GBK
 */
void CGBK2UnicodeDlg::OnReverseText()
{
 UpdateData(TRUE);

 int wc = MultiByteToWideChar(CP_UTF8,0,m_txt_input,m_txt_input.GetLength(),0,0);

 wchar_t* sUnicode = new wchar_t[wc+1];
 sUnicode[wc] = 0;

 MultiByteToWideChar(CP_UTF8,0,m_txt_input,m_txt_input.GetLength(),sUnicode,wc);
 
 CString unicode(sUnicode);
 SetDlgItemText(IDC_UNICODE_TEXT, unicode);

 if(sUnicode)
  delete[] sUnicode;

 GetDlgItem(IDC_GBK_TEXT)->SetFocus();
}