【C++】代码实现：std::string 转换为 UTF-8 编码

// std::string 转换为 UTF-8 编码
std::string string_To_UTF8(const std::string & str)
{
	int nwLen = ::MultiByteToWideChar(CP_ACP, 0, str.c_str(), -1, NULL, 0);

	wchar_t * pwBuf = new wchar_t[nwLen + 1];//一定要加1，不然会出现尾巴 
	ZeroMemory(pwBuf, nwLen * 2 + 2);

	::MultiByteToWideChar(CP_ACP, 0, str.c_str(), str.length(), pwBuf, nwLen);

	int nLen = ::WideCharToMultiByte(CP_UTF8, 0, pwBuf, -1, NULL, NULL, NULL, NULL);

	char * pBuf = new char[nLen + 1];
	ZeroMemory(pBuf, nLen + 1);

	::WideCharToMultiByte(CP_UTF8, 0, pwBuf, nwLen, pBuf, nLen, NULL, NULL);

	std::string retStr(pBuf);

	delete[]pwBuf;
	delete[]pBuf;

	pwBuf = NULL;
	pBuf = NULL;

	return retStr;
}