VC++中 wstring和string的互相转换实现

在VC++开发中，经常会用到string和wstring，这就需要二者之间的转换，项目中封装了wstring和string相互转换的2个函数，实现如下：

//将wstring转换成string
std::string ConvertWStringToAnsi(std::wstring wstr)
{
	std::string result;
	int len = WideCharToMultiByte(CP_ACP, 0, wstr.c_str(), wstr.size(), NULL, 0, NULL, NULL);
	if( len <= 0 )
		return result;

	char* buffer = new char[len + 1];
	if(buffer == NULL )
		return result;

	WideCharToMultiByte(CP_ACP, 0, wstr.c_str(), wstr.size(), buffer, len, NULL, NULL);
	buffer[len] = '\0';               //字符串断尾
	result.append(buffer);            //赋值
	delete[] buffer;                  //删除缓冲区

	//返回值
	return result;
}

//将string转换成wstring
std::wstring ConvertAnsiToWString(std::string str)
{
	std::wstring result;

	int len = MultiByteToWideChar(CP_ACP, 0, str.c_str(), str.size(), NULL, 0);
	if( len < 0 )
		return result;

	wchar_t* buffer = new wchar_t[len + 1];
	if( buffer == NULL )
		return result;

	MultiByteToWideChar(CP_ACP, 0, str.c_str(), str.size(), buffer, len);

	buffer[len] = '\0';                    //字符串断尾
	result.append(buffer);                 //赋值
	delete[] buffer;                       //删除缓冲区

	//返回值
	return result;
}