port number in RtlIpv4AddressToStringEx

[Lucassergei]

Syntax
CopyLONG NTAPI RtlIpv4AddressToStringEx(
__in const IN_ADDR *Address,
__in USHORT Port,
__out LPTSTR AddressString,
__inout PULONG AddressStringLength
);

Parameters
Address [in]
The IPv4 address in network byte order.

Port [in]
The port number in network byte order format. This parameter is optional.

AddressString [out]

The port number is optional. I don't understand . Could someone please clarify a bit ?

Thank you////

[Igor Vartanov]

Optional means it may or may be not specified. If zero, it gets omitted in the resultant address string.

#include <winsock2.h>
#include <windows.h>
#include <stdio.h>
#include <tchar.h>
#include <winsock2.h>
#include <MSTcpIP.h>

#pragma comment(lib, "ntdllstub")

#define COUNTOF(x) (sizeof(x)/sizeof(x[0]))

int main(int argc, LPCTSTR* argv)
{
	IN_ADDR addr = {0};
	USHORT port = 0;
	TCHAR addrStr[64] = {0};
	ULONG cch = COUNTOF(addrStr);
	LPTSTR delim = NULL;

	if (argc > 1)
		port = htons(atoi(argv[1]));

	if (NO_ERROR == RtlIpv4StringToAddress(TEXT("192.168.0.1"), TRUE, &delim, &addr))
	{
		if (NO_ERROR == RtlIpv4AddressToStringEx(&addr, port, addrStr, &cch))
			_tprintf(TEXT("IP = &#37;s\n"), addrStr);
	}

	return 0;
}

E:\Temp\598>598.exe
IP = 192.168.0.1

E:\Temp\598>598.exe 2011
IP = 192.168.0.1:2011