Questions on UDP Packet Transfers and C++

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Hello Code Project Community,

I am trying to use UDP, but I have the following questions:

1) I am trying to build a function that would recieve a simple UDP packet with a string like "/location 7 5" and parse out the float value 7 and 5 out and store it into an array. Are there any examples on how to do this?

2) After trying to use OSCPacket from https://code.google.com/p/oscpack/ for hours, I cannot get past any compiler errors shown here: http://i.tylian.net/untitloxo.png

As the error message suggests, the error comes from the OSCPack and not my code. Is anyone familiar with this or is there a better method to implement UDP packet transfers?

3) I am only using the ws32.dll library, but are there any other libraries I should be using besides that?

Feel free to respond to some or all of the multipart question and let me know if more detail is needed! Also, my target platform is Windows 7 64-bit.

Thank you very much for your time!

Posted 12-Mar-13 18:17pm

Member 9906083

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Mohibur Rashid 13-Mar-13 1:32am

You are transferring number, then why udp? why not tcp?

Member 9906083 13-Mar-13 1:47am

The reason is because I am trying to do a one-way transfer of commands, basically of many xy coordinates, so I thought udp would be simplier to implement.

Mohibur Rashid 13-Mar-13 1:53am

UDP Is best fit for media like stream, such as audio or video. Here you would need loss less data transmission. so, your best choice would be TCP.

Member 9906083 13-Mar-13 2:26am

I actually am using a module that is already written to send out UDP packets for me, and unfortunately, the client does not want to change their code.

Do you think maybe somehow I can catch a UDP packet with TCP?

Mohibur Rashid 13-Mar-13 2:35am

I dont have deep knowledge TCP and UDP internal work way. I am not sure whether you can do what you want to do, anyway, go to google and look for UDP example

Albert Holguin 13-Mar-13 10:57am

No... you can't do that, and you don't have to. He's wrong about you needing TCP for this. UDP is perfectly fine for this application.

Albert Holguin 13-Mar-13 10:56am

He doesn't need lossless transmission on something that's transmitting it's location. UDP is fine for this.

Mohibur Rashid 14-Mar-13 0:10am

This is interesting. Now I am trying to understand what can be the reason where client would need the location but if it lost no biggie. humm. Is this somekind of map application ??

Richard MacCutchan 13-Mar-13 6:44am

There are plenty of samples available on the use of sockets to receive TCP or UDP messages. Try a Google search for "udp socket".

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Jochen Arndt · Answer 1 · 2013-03-13T01:01:00

The WinSock library provides all required functions. There is no need to use other packages. See one of the plenty WinSock FAQs and Tutorials in the web on how to setup an UDP listener. After setting up the listener, just call WSARecvFrom().

The problem is that you don't know when and if data are coming in. So you should use a worker thread for receiving using overlapped IO (if WSARecvFrom() is pending, wait for the IO event and call GetOverlappedResult()). But this is also handled by the FAQs and tutorials.

Another problem is that your UDP packets may vary in their length. It is common practice to use some kind of header that identifies the type and size of data. But with short strings, you should get them with one read.

Albert Holguin · Answer 2 · 2013-03-13T05:06:00

Addressed your questions by number:
1. There's a ton of examples of this on the internet, just google "UDP C++ example" and you'll get a ton of hits. Basically you just set up your socket and just start listening (UDP doesn't really have a handshake process), every packet is a set of bytes (a datagram), it's up to you to cast these bytes onto a structure that breaks it out into interpreted data.

2. You can use the Windows sockets as described in Solution 1 or you can use a third-party library. Usually third party libraries just try to make the process easier or provide cross-platform sockets. Can't help you with this particular library but looking at the error, you probably have some sort of setup problem (didn't include files you needed or something similar).

3. MSDN tells you everything you need to know.
http://msdn.microsoft.com/en-us/library/windows/desktop/ms740673(v=vs.85).aspx[^]

Questions on UDP Packet Transfers and C++

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