Interesting alternate use for an API

[donkey]

Yup, you're right, the message remains until the Windows session ends.

[jj2007]

No, when application was ended, registered messages was *not* deleted. They stay registered until system reboot. Try to get a string from GetClipboardFormatName for an atom which you get earlyer in other running, and you will see.

Testbed... Alex is right. Still, it has an advantage over WM_COPYDATA since the latter would not work with console app.

Code Select Expand

include \masm32\include\masm32rt.inc

.data?
MessageName dd 2048 dup(?)

.code
TheString db "A test string designed for 'InterProcessCommunication' aka IPC;", 13, 10, "it works also with special characters, and you can insert CrLf easily.",13, 10,\
"The string can be a little bit longer, but it should not exceed 256 characters,", 13, 10, "apparently. Beyond 256, it will chok", 0

start: invoke SetLastError, 0
print "Testing RegisterWindowMessage with a "
print str$(sizeof TheString), " byte string:", 13, 10
Round1=1
if Round1
invoke RegisterWindowMessage, offset TheString
else
mov eax, 49799 ; on first round, I see this value
endif
push eax
print str$(eax), 9
print LastError$(), 13,10
pop eax
invoke GetClipboardFormatName,eax,offset MessageName, sizeof MessageName
print LastError$(), 13,10
print offset MessageName
exit
end start


[Antariy]

Yup, you're right, the message remains until the Windows session ends.

Anyway, your trick is very useful. For message scanners etc.

[dedndave]

you mean console apps cannot share memory ?
i have never had a need to do this - but it would be cool to know how   :bg

[jj2007]

you mean console apps cannot share memory ?

The problem is that console apps typically have no message loop/WndProc where you could check for WM_COPYDATA.

[dedndave]

hmmmm
another thing i haven't tried yet   :P
create a console proc, (i.e. no gui window) with a WndProc
well - that seems easy enough
that's what happens when i accidently link a gui app as console   :bg

[jj2007]

create a console proc, (i.e. no gui window) with a WndProc

If you create a GUI app with subsystem console, you will have a console for printing. Everything else works as usual.

I forgot to mention that you can send WM_COPYDATA from a console.

[dedndave]

that's what i said   :bg