C++ 多字节string转UTF-8 string

需求:数据库数据格式为UTF-8,本地VS工程编码字符集为多字节字符集,导入到本地csv文件时需要转化多字节std::string为UTF-8  std::string

接口与实现:

#include <Windows.h>
#include <string>

//以下为main需要的头文件,接口实现不需要
#include <iostream>
#include <fstream>
using namespace std;

std::wstring MultiChartoWideChar(std::string str)
{
    int nLen = MultiByteToWideChar(CP_ACP, 0, str.c_str(), (int)(str.size()), NULL, 0);
    WCHAR *pBuffer = new WCHAR[nLen + 1];
    MultiByteToWideChar(CP_ACP, 0, str.c_str(), (int)(str.size()), pBuffer, nLen);
    pBuffer[nLen] = '\0';
    std::wstring wstr;
    wstr.append(pBuffer);
    delete[] pBuffer;
    return wstr;
}

std::string WideChartoMultiChar(std::wstring wstr)
{
    int nLen = WideCharToMultiByte(CP_UTF8, 0, wstr.c_str(), (int)(wstr.size()), NULL, 0, NULL, NULL);
    CHAR *pBuffer = new CHAR[nLen + 1];
    WideCharToMultiByte(CP_UTF8, 0, wstr.c_str(), (int)(wstr.size()), pBuffer, nLen, NULL, NULL);
    pBuffer[nLen] = '\0';
    std::string str;
    str.append(pBuffer);
    delete[] pBuffer;
    return str;
}

std::string stringToUTF8string(std::string str)
{
    std::wstring wstr = MultiChartoWideChar(str);
    return WideChartoMultiChar(wstr);
}

int main()
{
    std::string str = "C++字符串编码转换";
    cout << "源字符串:" << str << endl;
    cout << "UTF8字符串:"<< stringToUTF8string(str) << endl;

    ofstream ofs;
    ofs.open("utf8.txt", ios::trunc);
    ofs << stringToUTF8string(str) << endl;
    ofs.close();

    system("Pause");
    return 0;
}