测试环境： vs2008

开发语言：C++

#include <iostream>
#include <windows.h>
#include <string>

// wchar_t to string
void Wchar_tToString(std::string& szDst, wchar_t *wchar)
{
wchar_t * wText = wchar;
DWORD dwNum = WideCharToMultiByte(CP_OEMCP,NULL,wText,-1,NULL,0,NULL,FALSE);// WideCharToMultiByte的运用
char *psText; // psText为char*的临时数组，作为赋值给std::string的中间变量
psText = new char[dwNum];
WideCharToMultiByte (CP_OEMCP,NULL,wText,-1,psText,dwNum,NULL,FALSE);// WideCharToMultiByte的再次运用
szDst = psText;// std::string赋值
delete []psText;// psText的清除
}

// string to wstring
void StringToWstring(std::wstring& szDst, std::string str)
{
std::string temp = str;
int len=MultiByteToWideChar(CP_ACP, 0, (LPCSTR)temp.c_str(), -1, NULL,0); 
wchar_t * wszUtf8 = new wchar_t[len+1]; 
memset(wszUtf8, 0, len * 2 + 2); 
MultiByteToWideChar(CP_ACP, 0, (LPCSTR)temp.c_str(), -1, (LPWSTR)wszUtf8, len);
szDst = wszUtf8;
std::wstring r = wszUtf8;
delete[] wszUtf8;
}


int main(int argc, char *argv)
{

// wchar_t  to string
std::string szDest;
wchar_t wText[20] = {L"宽字符转换字符串实例!OK!"};
Wchar_tToString(szDest, wText);
std::cout<<"szDest: "<<szDest<<std::endl;


/**
*wchar_t 定义的变量为什么不能输出呢？
*宽字符类型要本地化，否则输不出想要结果。
*本地化有三条语句可以使用，任取其一。最后一句是全局函数，前两个是wcout的一个成员函数的两种表达方式。
*/
//std::wcout.imbue(std::locale("chs"));
//std::wcout.imbue(std::locale(""));
setlocale(LC_ALL,"Chinese-simplified");

// string to wstring
std::string szSrc = "http://www.mamicode.com/字符串转换宽字符实例!OK!";
std::wstring wszDest;
StringToWstring(wszDest, szSrc);
std::wcout << "wszDest: " << wszDest << std::endl;

/**
    string to wchar_t
 */

string str= "字符串转换宽字符实例!OK!";
std::wstring widstr = std::wstring(str.begin(), str.end());
const wchar_t *pwidstr = widstr.c_str();

// 此方法简单，但是 delete wc;时会出异常
wchar_t   *   wc   =   new   wchar_t[szSrc.size()]; 
swprintf(wc,L"%S ",szSrc.c_str());//注意大写S。。 
std::wcout <<"szSrc: " << wc <<std::endl;
//delete wc;

system("PAUSE");
}