方式一：调用Windows API

#include <Windows.h>
//将string转换成wstring  
wstring string2wstring(string str)  
{  wstring result;  //获取缓冲区大小，并申请空间，缓冲区大小按字符计算  int len = MultiByteToWideChar(CP_ACP, 0, str.c_str(), str.size(), NULL, 0);  TCHAR* buffer = new TCHAR[len + 1];  //多字节编码转换成宽字节编码  MultiByteToWideChar(CP_ACP, 0, str.c_str(), str.size(), buffer, len);  buffer[len] = '\0';             //添加字符串结尾  //删除缓冲区并返回值  result.append(buffer);  delete[] buffer;  return result;  
}  //将wstring转换成string  
string wstring2string(wstring wstr)  
{  string result;  //获取缓冲区大小，并申请空间，缓冲区大小事按字节计算的  int len = WideCharToMultiByte(CP_ACP, 0, wstr.c_str(), wstr.size(), NULL, 0, NULL, NULL);  char* buffer = new char[len + 1];  //宽字节编码转换成多字节编码  WideCharToMultiByte(CP_ACP, 0, wstr.c_str(), wstr.size(), buffer, len, NULL, NULL);  buffer[len] = '\0';  //删除缓冲区并返回值  result.append(buffer);  delete[] buffer;  return result;  
} 

方式二：采用ATL封装_bstr_t的过渡

#include <comutil.h>  
#pragma comment(lib, "comsuppw.lib")string ws2s(const wstring& ws)
{_bstr_t t = ws.c_str();  char* pchar = (char*)t;  string result = pchar;  return result;  
}wstring s2ws(const string& s)
{_bstr_t t = s.c_str();  wchar_t* pwchar = (wchar_t*)t;  wstring result = pwchar;  return result; 
} 

以上转载自
https://blog.csdn.net/liminwang0311/article/details/79975174
另外C++ 11 好像还支持一下这种

// string_cvt.cpp : 此文件包含 "main" 函数。程序执行将在此处开始并结束。
//#include "pch.h"
#include <iostream>
#include <string>
#include <codecvt>using namespace std;
int main()
{wstring str = L"中国人";wstring_convert<codecvt<wchar_t, char, mbstate_t>> converter(new codecvt<wchar_t, char, mbstate_t>("CHS"));string narrowStr = converter.to_bytes(str);wstring wstr = converter.from_bytes(narrowStr);cout << narrowStr << endl;wcout.imbue(locale("chs"));wcout << wstr << endl;
}

以上转载自
https://blog.csdn.net/zang141588761/article/details/85600249