Windows C program performs shutdown action

Question

I am making a program that sends "heartbeats" to the server to track nodes. These are packages with the following payloads:

• 'start' at startup

• 'running' every 5 seconds

• "stop" when turned off

The first two are easy. A thread / loop can set a message for the first and subsequent starts. How to make the loop "catch" shutdown so that it can send the last packet?

I am using the minGW compiler for the C platform in WinXP.

Edit: I added relevant details that I missed (thanks walkTarget and Ferruccio)

• This is an unfinished application that contains messy things in the implementation :-)
• It uses libCURL, the HTTP client library to send packets
• This is a console application that I (much later) intend as a service
• It should save the file and send the package at shutdown
• He needs to fix the system shutdown

Answer 1

In your WindowProc (), you can check the WM_QueryEndSession message that Windows sends to all open processes before closing. For more information about this post, see the following link, but I understand that this is as trivial as the WM_SIZE check:

http://msdn.microsoft.com/en-us/library/aa376890%28VS.85%29.aspx