how to convert wstring to string

#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <string>
#include <locale>
#include <codecvt>
#include <fstream>
#include <sstream>
#include <afxwin.h>
using namespace std;


int main()
{
	setlocale(LC_CTYPE, "chs");
	string str;
	wstring wstr = L"123呵呵呵abc";
	char cstr[100] = {0};
	sprintf(cstr, "%S", wstr.c_str());
	str = cstr;
	cout << str << endl;
}

写入文件

#include <iostream>
#include <string>
#include <locale>
#include <codecvt>
#include <fstream>

int main(int argc, char *argv[])
{
   std::wstring str = L"123,我是谁？我爱钓鱼岛！";

   std::wstring_convert<std::codecvt_utf8<wchar_t>> conv;

   std::string narrowStr = conv.to_bytes(str);
   {
      std::ofstream ofs ("c:\\test.txt");
      ofs << narrowStr;
   }

   std::wstring wideStr = conv.from_bytes(narrowStr);
   {
      std::locale::global(std::locale("Chinese-simplified"));
      std::wofstream ofs (L"c:\\testW.txt");
      ofs << wideStr;
   }
｝

UTF8文件读取

#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <string>
#include <locale>
#include <codecvt>
#include <fstream>
#include <sstream>
#include <afxwin.h>
using namespace std;


int main()
{
	auto LocUtf8 = locale(locale(""),new codecvt_utf8<wchar_t>);
	wifstream wfin("test.txt");
	wfin.imbue(LocUtf8);
	wstring wstr;
	while (getline(wfin, wstr))
	{
		wcout.imbue(locale(""));
		wcout << wstr << endl;
	}
	wfin.close();
}

假如我们取到 的数据是这样的：

{"ret":1,"start":"58.57.64.0","end":"58.57.95.255","country":"\u4e2d\u56fd","province":"\u5c71\u4e1c","city":"\u6f4d\u574a","district":"","isp":"\u7535\u4fe1","type":"","desc":""}

http://int.dpool.sina.com.cn/iplookup/iplookup.php?format=json&ip=58.57.91.184

那么我们改怎么样进行转化呢？

zhaoshizhong1老师的方法：

#include <cstdio>
#include <locale>
#include <iostream>
using namespace std;

#define MAXL 100
char u[]="\\u4e2d\\u56fd", *p;
wchar_t us[MAXL];
char str[MAXL];
int i;
int main()
{
	setlocale(LC_ALL, "chs");
	//_wsetlocale(LC_ALL, L"chs");
	//std::locale loc = (std::locale("Chinese-simplified"));
	i = 0;
	p = u;
	while (true)
	{
		if (1 != sscanf(p, "\\u%4hx", &us[i])) break;
		i++;
		if (i >= MAXL - 1) break;
		p += 6;
	}
	us[i] = 0;
	//wcout.imbue(loc);
	sprintf(str, "%S", us);
	//wcout << us << endl;
	cout << str << endl;
	return 0;
}
//u:[\u5c71\u4e1c]
//us:[山东]
//