Environment: VC6, WIN XP SP1
While I was writing a LAN (Local Area Network) chat program, I noticed that many people on my LAN use different programs for message sending and that not all of them are compatible with other programs. The second problem I noticed was that many of them don’t work on Win95/98. So, I decided to add this functionality to my program. I started to search for a universal method for all Windows versions and most message-sending programs and I discovered that the best solution is to add a MAILSLOT mechanism to my program (along with some others). The first place I searched was MSDN and CodeGuru, but I didn’t find any complete solution. That’s the main reason I wrote this article.
I wrote a function that writes to the mailslot (I saw how to do that on CodeGuru) and a simple class that reads from the mailslot (I found many explanations and put all of them together—mostly from “PJ Naughter”). I also wrote a simple project so you can see how to link these two things and put everything in the right places.>
Here are the steps you need to do:
- Add “mailslot.h” and “mailslot.cpp” to your project.
- Create a CMailSlot instance in your main class (for example, m_serverMailSlot).
- Add an OnTimer event to your project and somewhere set the Timer. For example, you can do that in OnInitDialog():
SetTimer(timerID, 2000, NULL); //this is for 2 seconds
- Create a CheckForNewMessage() function. That is the place where you will be calling an m_serverMailSlot.Read() function.
- In the OnTimer() function, call the CheckForNewMessage() function, which will check for new messages and display them (if there are any waiting).
That is all. I know that there are better ways to send messages, but this is the most-used method so you will be able to receive messages from many different programs and to use it on any Windows operating system.
If you have any questions or need some extra help with this, e-mail me… If there are any suggestions or comments, you are most welcome to contact me, too.
You can download “mailslot.h”, “mailslot.cpp” (contains CServerMailslot), and “sendfun.txt”. You can also download the sample project and executable file.