convert between Big-endian(TCP/IP network) byte order and Little-endian(host) byte order

htons-htonl-ntohs-ntohl.cpp

namespace nh {

	auto htons = [](unsigned short h)
	{
		return (unsigned short)
			   ( h << 8 & 0xFF00U |
			     h >> 8 & 0x00FFU );
	};

	auto htonl = [](unsigned int h)
	{
		return (unsigned int)
			   ( h << 24 & 0xFF000000U |
			     h << 8  & 0x00FF0000U |
			     h >> 8  & 0x0000FF00U |
			     h >> 24 & 0x000000FFU );
	};

	auto ntohs = htons;
	auto ntohl = htonl;

}

/*------ test code -----------
// vs2017 on win7

#include <iostream>
#include <Winsock2.h>

#pragma comment(lib, "ws2_32.lib")

void byte_order()
{

	unsigned short a = 0x1234U;

	std::cout << std::showbase << std::hex;
	std::cout << "a = " << a << std::endl;

	std::cout << "ntohs(a) = " << ntohs(a) << std::endl;
	std::cout << "htons(a) = " << htons(a) << std::endl;
	std::cout << "nh::htons(a) = " << nh::htons(a) << std::endl;
	std::cout << "nh::ntohs(a) = " << nh::ntohs(a) << std::endl;

	unsigned b = 0x12345678u;

	std::cout << "b = " << b << std::endl;

	std::cout << "ntohl(b) = " << ntohl(b) << std::endl;
	std::cout << "htonl(b) = " << htonl(b) << std::endl;
	std::cout << "nh::htonl(b) = " << nh::htonl(b) << std::endl;
	std::cout << "nh::ntohl(b) = " << nh::ntohl(b) << std::endl;

}

int main()
{
	byte_order();

}

------------------------------*/

/*------ test code output-----

a = 0x1234
ntohs(a) = 0x3412
htons(a) = 0x3412
nh::htons(a) = 0x3412
nh::ntohs(a) = 0x3412
b = 0x12345678
ntohl(b) = 0x78563412
htonl(b) = 0x78563412
nh::htonl(b) = 0x78563412
nh::ntohl(b) = 0x78563412

--------------------------------*/