C++ UFT-8和GB2312间的转换

在这个帖子找到的代码 还蛮好用的 https://bbs.csdn.net/topics/391040755

#include <codecvt>
#include <locale>
#include <vector>
using namespace std;
std::string gb2312_to_utf8(std::string const &strGb2312)
{
    std::vector<wchar_t> buff(strGb2312.size());
#ifdef _MSC_VER
    std::locale loc("zh-CN");
#else
    std::locale loc("zh_CN.GB18030");
#endif
    wchar_t* pwszNext = nullptr;
    const char* pszNext = nullptr;
    mbstate_t state = {};
    int res = std::use_facet<std::codecvt<wchar_t, char, mbstate_t> >
        (loc).in(state,
            strGb2312.data(), strGb2312.data() + strGb2312.size(), pszNext,
            buff.data(), buff.data() + buff.size(), pwszNext);

    if (std::codecvt_base::ok == res)
    {
        std::wstring_convert<std::codecvt_utf8<wchar_t>> cutf8;
        return cutf8.to_bytes(std::wstring(buff.data(), pwszNext));
    }

    return "";

}

std::string utf8_to_gb2312(std::string const &strUtf8)
{
    std::wstring_convert<std::codecvt_utf8<wchar_t>> cutf8;
    std::wstring wTemp = cutf8.from_bytes(strUtf8);
#ifdef _MSC_VER
    std::locale loc("zh-CN");
#else
    std::locale loc("zh_CN.GB18030");
#endif
    const wchar_t* pwszNext = nullptr;
    char* pszNext = nullptr;
    mbstate_t state = {};

    std::vector<char> buff(wTemp.size() * );
    int res = std::use_facet<std::codecvt<wchar_t, char, mbstate_t> >
        (loc).out(state,
            wTemp.data(), wTemp.data() + wTemp.size(), pwszNext,
            buff.data(), buff.data() + buff.size(), pszNext);

    if (std::codecvt_base::ok == res)
    {
        return std::string(buff.data(), pszNext);
    }
    return "";
}