C++ UTF8和GB2312相互转换

#include <Windows.h>
#include <string>
using std::string;

void UTF8_to_GB2312(const char* utf8, string& gb2312_str)
{
    int len = MultiByteToWideChar(CP_UTF8, , utf8, -, NULL, );
    wchar_t* wstr = new wchar_t[len+];
    memset(wstr, , len+);
    MultiByteToWideChar(CP_UTF8, , utf8, -, wstr, len);
    len = WideCharToMultiByte(CP_ACP, , wstr, -, NULL, , NULL, NULL);
    char* str = new char[len+];
    memset(str, , len+);
    WideCharToMultiByte(CP_ACP, , wstr, -, str, len, NULL, NULL);
    delete[] wstr;
    gb2312_str = str;
    delete[] str;
    return;
}

void GB2312_to_UTF8(const char* gb2312, string& utf8_str)
{
    int len = MultiByteToWideChar(CP_ACP, , gb2312, -, NULL, );
    wchar_t* wstr = new wchar_t[len+];
    memset(wstr, , len+);
    MultiByteToWideChar(CP_ACP, , gb2312, -, wstr, len);
    len = WideCharToMultiByte(CP_UTF8, , wstr, -, NULL, , NULL, NULL);
    char* str = new char[len+];
    memset(str, , len+);
    WideCharToMultiByte(CP_UTF8, , wstr, -, str, len, NULL, NULL);
    delete[] wstr;
    utf8_str = str;
    delete[] str;
    return;
}