Convert char array to Hex String

CharArrayToHex

string CharArrayToHex(char* data, size_t len)
{
	constexpr char hexmap[] = { '0', '1', '2', '3', '4', '5', '6', '7',
							   '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };
	std::string s(len * 2, ' ');
	unsigned char p;
	for (int i = 0; i < len; ++i) {
		p = data[i];
		s[2 * i] = hexmap[(p & 0xF0) >> 4];
		s[2 * i + 1] = hexmap[p & 0x0F];
	}
	return s;
}