[WhiteTree]

Hello,

Iam trying to create a timeclient that connects to a timeserver on port 37, sends an empty datagram and recieves the time from that server. When I recieve the time from the server (an integer representing the number of seconds passed since midnight january 1st 1900) I need to subtract 2208988800 (70 years worth of seconds) so I can use the ctime function in C (which displays the time since 1970).

Its quite simple, however, the problem is that the ctime function displays my time(the current time of my PC) not the time of the timeserver.
How do I display the time of the timeserver (not my current time)? Also anyway to change the display of the time from army time (24 oclock) to 12 hour time?

Thanks.

[Regicide]

First off, what OS are you dealing with? Secondly, what you might want to try it to send the time as string and then recieve it and use the atoi() function to get it into an integer. Am I correct to say that you are using UDP? Once you get it into a time format, you can simply have a if statement for converting to 12 hours time:

int hour;
bool pm;
if(hour > 12)
{
hour -= 12;
pm = true;
} esle {
pm = false;
}

Hope this helps.

[WhiteTree]

Yes, Im using UDP. Im also working in Windows but using Xwindows. However, the way a timeserver works is that the client sends an empty datagram (UDP) and the Time server then responds by sending an integer representing the number of seconds since midnight Jan 1st 1900. Now the ctime function in C returns the number seconds since midnight Jan 1 1970! and also returns it in a string format (Wed Jan 5 etc....). To make the ctime function work you need to convert the number recieved from the timeserver (seconds since 1900) to midnight jan 1st 1970 (you simply subtract the number of seconds in 70 years). This is all well and good, but for some reason the converted time is my system time! not the time server time. Its really annoying. Lets say Its 1 pm on the west, if I contact a timeserver in the east, I should get back 4 pm ( a 3 hour differenct), but nope, I recieve 1 pm.

[codejockey]

Well, the number of seconds since 1970 (or 1900) is still the same, whether or you are on the East coast, the West coast or anywhere else; it's how we interpret them that counts. You might consider adjusting the result to the timezone of the server that you connect with, if this is really what you intend ...

Note that the ctime function returns the local time based on a calendar interval; as long as you use this function, you will receive the local time.

Hope this helps.

[WhiteTree]

Thanks that cleared up the reason for it always displaying my time.

But do you know of any function that simply displays the time as a string without converting it to the local time?

thanks

[codejockey]

The "time" is always local -- i.e., relative to some location/time zone. The same moment that is 9:00 A.M. in New York is 6:00 A.M. in California, so a string such as "9:00 A.M. May 29, 2004" is ambiguous, at best -- which is why the server reports an elapsed interval (number of seconds since some reference point) instead. The interval can be converted to the "local" equivalent; if the server reported its "local time" (i.e., did the conversion), you would have to know the time zone/location of the server in order to interpret the result.

If you really want to know the local time at the server when the request is made, you will need to adjust the reported value manually, based on the difference between your time zone and that of the server, and then use the ctime function to produce an ascii string.

Hope this helps.