Call a specific function when the console program terminates - c

Question

I'm on windows and I want to call a specific function when the program terminates.
For example:
void close_program()
{
/*do stuff*/
printf("Goodbye.\n");
}
I tried atexit() but it only worked on casual and regular exits such as a call to the function exit() or when the main returns a value to the OS.
I found out that HandlerRoutine() seems like a solution as windows sends a CTRL_CLOSE_EVENT value signal to the process closed by the user (either just close button or end task through task manager). The problem is I tried a really basic piece of code and it said 'undefined reference to HandlerRoutine' and that it returned 1.
The piece of code:
#include <stdio.h>
#include <windows.h>
int main()
{
while(1)
{
if(HandlerRoutine(CTRL_CLOSE_EVENT))
{
printf("Program is being terminated...\n");
}
}
return 0;
}
I use MinGW.
Any idea what is the problem might be ?
According to MSDN there is no need for linkage.

Answer 1

HandlerRoutine is the callback function that will be invoked when console will be terminated. It's not the function you have to call but the signature (defined as HANDLER_ROUTINE) of your function (that will be invoked by Windows itself):
BOOL WINAPI HandlerRoutine(DWORD dwCtrlType);
You'll inspect dwCtrlType to check for CTRL_CLOSE_EVENT returning (usually) TRUE. To attach your function and make it called you have to use SetConsoleCtrlHandler() API function, like this:
BOOL YourHandler(DWORD dwCtrlType)
{
if (CTRL_CLOSE_EVENT == dwCtrlType)
{
}
return TRUE;
}
Now you have your function but you instruct Windows to call it:
int main()
{
SetConsoleCtrlHandler((PHANDLER_ROUTINE)YourHandler, TRUE);
// Do your stuff here
return 0;
}
Please note that you can register more than one handler, they'll be called in chain up to the one that returns TRUE. For a complete example just consult MSDN.

Answer 2

From the MSDN page you linked
HandlerRoutine is a placeholder for the application-defined function name.
What you need to do is create a callback (of PHANDLER_ROUTINE type) and then use SetConsoleCtrlHandler to register this callback.

Answer 3

Try including wincon.h explicitly. I know there are a number of child header files that are automatically included with windows.h but many of these files cannot simply be included by themselves (they are not self-contained), because of dependencies. wincon.h is one such child header file used for console services.