宽字符和窄字符之间的转换，以及对中文的处理问题总汇

直接代码：

注：编译环境VS2010 SP1

/*实现宽字节和窄字符转换以及中文文件的输入输出*/

#include <iostream>
#include <string>
#include <fstream>
#include <locale>
#include <codecvt>
#include <windows.h>
#include <tchar.h>
using namespace std;

//-----------------------------------------------------------------------------
//转换宽窄字符串时可以成功，并且支持中文转换
const std::wstring s2ws(const std::string& s)
{
    std::locale old_loc = std::locale::global(std::locale(""));
    const char* src_str = s.c_str();
    const size_t buffer_size = s.size() + 1;
    wchar_t* dst_wstr = new wchar_t[buffer_size];
    wmemset(dst_wstr, 0, buffer_size);
    mbstowcs(dst_wstr, src_str, buffer_size);
    std::wstring result = dst_wstr;
    delete []dst_wstr;
    std::locale::global(old_loc);
    return result;
}
const std::string ws2s(const std::wstring& ws)
{
    std::locale old_loc = std::locale::global(std::locale(""));
    const wchar_t* src_wstr = ws.c_str();
    size_t buffer_size = ws.size() * 4 + 1;
    char* dst_str = new char[buffer_size];
    memset(dst_str, 0, buffer_size);
    wcstombs(dst_str ,src_wstr, buffer_size);
    std::string result = dst_str;
    delete []dst_str;
    std::locale::global(old_loc);
    return result;
}

//-----------------------------------------------------------------------------
//转换宽窄字符串时可以成功，并且支持中文转换
std::string WChar2Ansi(LPCWSTR pwszSrc)
{
    int nLen = WideCharToMultiByte(CP_ACP, 0, pwszSrc, -1, NULL, 0, NULL, NULL);

    if (nLen<= 0) return std::string("");

    char* pszDst = new char[nLen];
    if (NULL == pszDst) return std::string("");
    ZeroMemory(pszDst, nLen);

    WideCharToMultiByte(CP_ACP, 0, pwszSrc, -1, pszDst, nLen, NULL, NULL);
    pszDst[nLen -1] = 0;

    std::string strTemp(pszDst);
    delete [] pszDst;

    return strTemp;
}
std::wstring Ansi2WChar(LPCSTR pszSrc, int nLen)

{
    int nSize = MultiByteToWideChar(CP_ACP, 0, (LPCSTR)pszSrc, nLen, 0, 0);
    if(nSize <= 0) return NULL;

    WCHAR *pwszDst = new WCHAR[nSize+1];
    if( NULL == pwszDst) return NULL;
    ZeroMemory(pwszDst, nSize);

    MultiByteToWideChar(CP_ACP, 0, pszSrc, nLen, pwszDst, nSize);
    pwszDst[nSize] = 0;

    if( pwszDst[0] == 0xFEFF) // skip Oxfeff
        for(int i = 0; i < nSize; i ++)
            pwszDst[i] = pwszDst[i+1];

    wstring wcharString(pwszDst);
    delete pwszDst;

    return wcharString;
}

//-----------------------------------------------------------------------------
//虽然可以转换宽窄字符串，但是不能解决中文乱码问题
std::wstring strtowstr(const std::string &i_str)
{
    std::wstring_convert<std::codecvt_utf8<wchar_t>> conv;
    std::wstring l_wstr = conv.from_bytes(i_str);
    return l_wstr;
}
std::string wstrtostr(const std::wstring &i_wstr)
{
    std::wstring_convert<std::codecvt_utf8<wchar_t>> conv;
    std::string l_str = conv.to_bytes(i_wstr);
    return l_str;
}

//-----------------------------------------------------------------------------
bool OutputFile(const string &i_strFileName, const string &i_strExt)
{
    std::locale old_loc = std::locale::global(std::locale(""));
    ofstream ofs(i_strFileName, ifstream::out|ifstream::binary);
    if (ofs.rdstate()!=ios_base::goodbit)
    {
        cout << "open file error." << endl;
        return false;
    }
    ofs.write(i_strExt.c_str(), i_strExt.length());
    ofs.clear();
    ofs.close();
    std::locale::global(old_loc);
    return true;
}
bool OutputFileW(const string &i_strFileName, const wstring &i_wstrExt)
{
    std::locale old_loc = std::locale::global(std::locale(""));
    wofstream wofs(i_strFileName, ifstream::out|ifstream::binary);
    if (wofs.rdstate()!=ios_base::goodbit)
    {
        wcout << L"open file error." << endl;
        return false;
    }
    wofs.write(i_wstrExt.c_str(), i_wstrExt.length());
    wofs.clear();
    wofs.close();
    std::locale::global(old_loc);
    return true;
}
//bool OutputFile2(const string &i_strFileName, const string &i_strExt)
//{
//    //1
//    //std::locale loc("");
//    //typedef codecvt<wchar_t, char, std::mbstate_t> facet_type;
//    //const std::locale::facet &myfacet = use_facet<facet_type>(loc);
//    //std::locale curloc(loc, &myfacet);
//
//    //std::locale loc("");
//    //std::codecvt_utf8_utf16<wchar_t> *pconv = new std::codecvt_utf8_utf16<wchar_t> ();
//    //std::locale curloc(loc, pconv);
//
//    ofstream ofs(i_strFileName, ifstream::out|ifstream::binary);
//    if (ofs.rdstate()!=ios_base::goodbit)
//    {
//        cout << "open file error." << endl;
//        return false;
//    }
//    ofs.imbue(std::locale(std::locale(""), new std::codecvt_utf8_utf16<wchar_t>));
//    //ofs.imbue(curloc);
//    ofs.write(i_strExt.c_str(), i_strExt.length());
//    ofs.clear();
//    ofs.close();
//
//    return true;
//}

//测试以上代码部分
void main()
{
    string strExt = "这是一个窄字符串";
    wstring wstrExt = L"这是一个宽字符串";

    //string strRet;
    //wstring wstrRet;
    //wstrRet = s2ws(strExt);
    //strRet = ws2s(wstrExt);
    //cout << strRet << endl;
    //wcout << wstrRet << endl;

    //string strFileName1 = "F:\Desktop\20140411\测试\output.txt";
    //bool f1 = OutputFile(strFileName1, strExt);
    //string strFileName2 = "F:\Desktop\20140411\测试\outputw.txt";
    //bool f2 = OutputFileW(strFileName2, wstrExt);

    //LPCWSTR pwstr = _TEXT("windows宽字符串");
    //std::string strResult = WChar2Ansi(pwstr);
    //cout << strResult << endl;
    //LPCSTR pstr = "windows窄字符串";
    ////size_t cnlen = lstrlenA(pstr);
    //size_t cblen = lstrlenA(pstr)*sizeof(CHAR);
    //std::wstring wstrResult = Ansi2WChar(pstr, cblen);
    //wcout << wstrResult << endl;

    //std::wstring wstr = L"wchar_t宽字符";
    //std::string strResult = wstrtostr(wstr);
    //cout << "宽字符转窄字符：" << strResult << endl;

    cout << endl;
}