C++ 字符串UTF8与GBK转化

       第一次写博客，有时候在工作中遇到解析XML文件，节点属性值为中文的情况，需要转换编码，VC默认是的是GB2312,遇到中文就出现乱码，下面是UTF-8和GBK2312的互相转换，有画蛇添足的地方，希望各位大神指出：

#include "windows.h"

// UTF-8转为GBK2312 [1/18/2017/shike]
 std::string UtfToGbk(const char* utf8)
 {
   int len = MultiByteToWideChar(CP_UTF8, 0, utf8, -1, NULL, 0);
   wchar_t* wstr = new wchar_t[len+1];
   memset(wstr, 0, len+1);
   MultiByteToWideChar(CP_UTF8, 0, utf8, -1, wstr, len);
   len = WideCharToMultiByte(CP_ACP, 0, wstr, -1, NULL, 0, NULL, NULL);
   char* str = new char[len+1];
   memset(str, 0, len+1);
   WideCharToMultiByte(CP_ACP, 0, wstr, -1, str, len, NULL, NULL);
   if(wstr) delete[] wstr;
   return str;
 }

//GBK转化为UTF8格式
 void ConvertGBKToUtf8(CString &strGBK)
 {
  int len=MultiByteToWideChar(CP_ACP, 0, (LPCTSTR)strGBK, -1, NULL,0);
  wchar_t * wszUtf8 = new wchar_t [len];
  memset(wszUtf8, 0, len);
  MultiByteToWideChar(CP_ACP, 0, (LPCTSTR)strGBK, -1, wszUtf8, len);
  len = WideCharToMultiByte(CP_UTF8, 0, wszUtf8, -1, NULL, 0, NULL, NULL);
  char *szUtf8=new char[len + 1];
  memset(szUtf8, 0, len + 1);
  WideCharToMultiByte (CP_UTF8, 0, wszUtf8, -1, szUtf8, len, NULL,NULL);
  strGBK = szUtf8;
  delete[] szUtf8;
  delete[] wszUtf8;
 }