ANSI，UNICODE，UTF8之间的相互转换

经常用到多字节，unicode之间转换，这次从网上摘抄了些代码，用以记录。

std::wstring AnsiToUnicode(const std::string &strAnsi)
{
	//获取转换所需的接收缓冲区大小
	int  nUnicodeLen = ::MultiByteToWideChar(CP_ACP,
		0,
		strAnsi.c_str(),
		-1,
		NULL,
		0);
	//分配指定大小的内存
	wchar_t* pUnicode = new wchar_t[nUnicodeLen + 1];
	memset((void*)pUnicode, 0, (nUnicodeLen + 1) * sizeof(wchar_t));

	//转换
	::MultiByteToWideChar(CP_ACP,
		0,
		strAnsi.c_str(),
		-1,
		(LPWSTR)pUnicode,
		nUnicodeLen);

	std::wstring  strUnicode;
	strUnicode = (wchar_t*)pUnicode;
	delete[]pUnicode;

	return strUnicode;
}

std::string UnicodeToANSI(const std::wstring& strUnicode)
{
	int nAnsiLen = WideCharToMultiByte(CP_ACP,
		0,
		strUnicode.c_str(),
		-1,
		NULL,
		0,
		NULL,
		NULL);

	char *pAnsi = new char[nAnsiLen + 1];
	memset((void*)pAnsi, 0, (nAnsiLen + 1) * sizeof(char));

	::WideCharToMultiByte(CP_ACP,
		0,
		strUnicode.c_str(),
		-1,
		pAnsi,
		nAnsiLen,
		NULL,
		NULL);

	std::string strAnsi;
	strAnsi = pAnsi;
	delete[]pAnsi;

	return strAnsi;
}

std::wstring UTF8ToUnicode(const std::string& str)
{
	int nUnicodeLen = ::MultiByteToWideChar(CP_UTF8,
		0,
		str.c_str(),
		-1,
		NULL,
		0);

	wchar_t*  pUnicode;
	pUnicode = new wchar_t[nUnicodeLen + 1];
	memset((void*)pUnicode, 0, (nUnicodeLen + 1) * sizeof(wchar_t));

	::MultiByteToWideChar(CP_UTF8,
		0,
		str.c_str(),
		-1,
		(LPWSTR)pUnicode,
		nUnicodeLen);

	std::wstring  strUnicode;
	strUnicode = (wchar_t*)pUnicode;
	delete []pUnicode;

	return strUnicode;
}

std::string UnicodeToUTF8(const std::wstring& strUnicode)
{
	int nUtf8Length = WideCharToMultiByte(CP_UTF8,
		0,
		strUnicode.c_str(),
		-1,
		NULL,
		0,
		NULL,
		NULL);

	char* pUtf8 = new char[nUtf8Length + 1];
	memset((void*)pUtf8, 0, sizeof(char) * (nUtf8Length + 1));

	::WideCharToMultiByte(CP_UTF8,
		0,
		strUnicode.c_str(),
		-1,
		pUtf8,
		nUtf8Length,
		NULL,
		NULL);

	std::string strUtf8;
	strUtf8 = pUtf8;
	delete[] pUtf8;

	return strUtf8;
}

std::string AnsiToUtf8(const std::string &strAnsi)
{
	std::wstring strUnicode = AnsiToUnicode(strAnsi);
	return UnicodeToUTF8(strUnicode);
}

std::string Utf8ToAnsi(const std::string &strUtf8)
{
	std::wstring strUnicode = UTF8ToUnicode(strUtf8);
	return UnicodeToANSI(strUnicode);
}