C / C++ / MFC

Re: Interprocess commmunication

7-Jul-07 11:41

What are the best ways to send messages from one process to other process?

Mark Salsbery7-Jul-07 12:10

7-Jul-07 12:10

The "best" way depends on the message type/size/etc.

For messages between windows or threads that can fit in two INT_PTR-sized variables there's
PostMessage()/PostThreadMessage() (note you can't pass pointers).

For larger "messages" between windows there's the WM_COPYDATA message.

For anything else...

Interprocess Communications[^]

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Notepad

tom groezer7-Jul-07 11:37

7-Jul-07 11:37

What does a notepad open two similar process when invoked on a single file. What is the rational. It looks logical to do that when doing it over a network between two machines.

Re: Notepad

David Crow9-Jul-07 3:47

David Crow

9-Jul-07 3:47

tom groezer wrote:
What does a notepad open two similar process when invoked on a single file.

Like other text editors/word processors, Notepad does not actually keep the file open. Therefore, when opening the same file more than once, Notepad does not communicate with other instances of itself to see what they are doing.

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Message queue

tom groezer7-Jul-07 11:35

7-Jul-07 11:35

Is there a way to set a size for message queue? Also is there any performance consideration to be made while selecting PeekMessage or GetMessage.

-- modified at 5:13 Sunday 8th July, 2007

Re: Message loop

Mark Salsbery7-Jul-07 11:56

7-Jul-07 11:56

tom groezer wrote:
Is there a way to set a size for message loop?

loops have a size? Smile | :)

tom groezer wrote:
is there any performance consideration to be made while selecting PeekMessage or GetMessage.

In a loop, yes. GetMessage() will wait for posted messages. PeekMessage() will not.
Looping calling PeekMessage() when no messages are available in the queue will use CPU time
needlessly.

Mark

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Re: Message queue

Blake Miller9-Jul-07 11:59

Blake Miller

9-Jul-07 11:59

I think you can set a quota.
I am pretty sure the upper limit is 10,000 messages.

We have abandoned 'window message queues' in a few areas because of the limit.

Given the nature of your other queries, you might want to consider using TCP/IP or named pipes for your interprocess communications.

CArchive

tom groezer7-Jul-07 11:34

7-Jul-07 11:34

How could I achieve versioning of archive files.

Re: CArchive

Mark Salsbery7-Jul-07 11:54

7-Jul-07 11:54

The simplest way would be to insert a version number when storing (before writing anything else)
and when loading, extract the version number and use it to appropriately load the archive.

Mark

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Console App Flicker

JimmyRopes7-Jul-07 10:07

JimmyRopes

7-Jul-07 10:07

I need to write a console application to write a state log. It will be executed as a task periodically and record the condition of things to a log file.

When I execute the application it causes the screen to flicker in the best of circumstances and a phantom console window to appear and disappear in the worst of circumstances even though I don’t write anything to the console. Everything is appended to a log file.

Is there any way of suppressing the flicker or phantom console window from appearing?

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Matthew Faithfull7-Jul-07 10:15

Matthew Faithfull

7-Jul-07 10:15

For similar problems I always recommend switching from a Console app to a Windows app and then not actually opening any Windows. Most of my test apps run that way.

Nothing is exactly what it seems but everything with seems can be unpicked.

JimmyRopes7-Jul-07 16:16

JimmyRopes

7-Jul-07 16:16

I was thinking about running a windows application instead of a console application but need to pass command line parameters. Is there a way to get the equivalent of the argv array when executing a windows app?

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Think inside the box! ProActive Secure Systems

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JimmyRopes

Mark Salsbery8-Jul-07 7:50

8-Jul-07 7:50

Check out the remarks section here: GetCommandLine()[^]

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JimmyRopes8-Jul-07 18:18

JimmyRopes

8-Jul-07 18:18

Mark Salsbery wrote:
GetCommandLine()

Excellent! That along with Mathew's suggestion to use a windows application is just what I need to get rid of the flicker.

Simply Elegant Designs JimmyRopes Designs
Think inside the box! ProActive Secure Systems

I'm on-line therefore I am.
JimmyRopes

Function overloading

tom groezer7-Jul-07 5:18

7-Jul-07 5:18

Can we overload a function by return type?

mid=57417-Jul-07 5:51

mid=5741

7-Jul-07 5:51

No[^].

Matthew Faithfull7-Jul-07 5:52

Matthew Faithfull

7-Jul-07 5:52

The simple answer is no. Two functions which differ only by return type are not allowed.

You can make a function return a template defined type but unless that type is also used for one of the parameters you're going to find it hard to get the compiler to recognise which type you intend to replace your template argument with in any given case. some experimentation required I think.
You could consider passing in the return value by reference and then you'd have no problem doing ordinary overloading.

int Myfunc(void)
{
}

//Error
float Myfunc(void)
{
}

void Myfunc(int& iRef)
{
}

//Happy
void Myfunc(float& fRef)
{
}

Nothing is exactly what it seems but everything with seems can be unpicked.

pagen_hd7-Jul-07 20:49

pagen_hd

7-Jul-07 20:49

No. Because when you call the function the compiler won't be able to know which overload you're calling.