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The lifetime of static objects for a DLL application is from the Load of your DLL up to the removal (often, program termination) from the executable it is used in.
Some extra information (though not entirely answering your question) can be found here: DllMain entry point[^]. In terms of this article, the static objects live from just before the call with DLL_PROCESS_ATTACH and just until after the call to DLL_PROCESS_DETACH.
Specifically for WriteCommMsg, it looks like the variable (MsgStr) is caller allocated, so you do not need to worry about lifetime of objects there. If msg is used to output data, just write it to the location pointed to. If it is used for input, either use it right away, or save it by copying it to a variable with the appropriate lifetime (probably static in that case).
Easiest way to look at a DLL is as just another executable, except for that it doesn't run stand-alone, but always as part of another executable.
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skaboFer wrote: WriteCommMsg(MsgStr * msg)", I don't know were to declare the necesary
variables
The caller would supply the variable, either stack, or heap based, so your dll wont need to worry about it.
skaboFer wrote: if I'd have to save the last send msg
Then your dll will have to allocate some stack memory and copy the message to it (alloc() or new).
As for lifetime, it is as long as you like with the heap. Remember to free it befoire your dll exits, because if not, you have a memory leak.
You could use static variables, these last the lifetime of the dll in memory.
==============================
Nothing to say.
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skaboFer wrote: I mean, my doubt is what is the lifetime of the variables in a dynamic win32 dll.
In general the only variables you shaould keep in your DLL are const values that will never change. All non-const variables should belong in your main program and be passed to the DLL routine as required, in the same way as in C#. In your sample function above you define a library function (in the DLL) with the signature
WriteCommMsg(MsgStr * msg)
Here msg is a pointer (reference in C#) to a variable of type MsgStr, but the actual data that msg refers to is stored within the application not the DLL, something like:
MsgStr myMsgString = "message to write"; WriteCommMsg(&myMsgString);
If you wish to keep variable data within your library routines during the lifetime of your application then you should use a static library rather than a DLL.
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First of all thanks!
Ok I understand the part of the pointer to the struct that tha main app pass to my function.
But you say that to keep data in my library I should use a static lib instead of a dll, but
could I just declare a static global variable/object?
And what do you think about the object to handle the serial port? where should I declare
the serialPort variable?
Again, thanks for the answers!
skabo - Robots are a dynamic work of art...
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skaboFer wrote: could I just declare a static global variable/object?
You could but it is generally not considered good form, you should use proper parameter passing between methods in the same way that you would in C#.
skaboFer wrote: where should I declare
the serialPort variable?
Again declare it in your main application and use the classes or functions in your library to access it without the need to know its actual values. If the code in your DLL becomes specific to the application then there is absolutely no point in creating the DLL in the first place, just put everything in the application.
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That's my point...this dll it's not for a especific application, it is a dll based in a norm that only specified the prototypes of the functions that the dll has to have, so then every user application could use it, but the user app doesn´t matter about de serial port...so I have to manage it in my dll...
thanks
skabo - Robots are a dynamic work of art...
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hello guys... I have a static library. Now I used this library with another project and compiled both of these. I got plenty of linking error (mostly LNK2001 and LNK2005). I went to both projects' properties and changed
Use of MFC: Use MFC in Shared DLL
Now question is: since the library is static, should I be using
Use of MFC: Use MFC in Static Library ? Some tutorial on it is more than welcome. thnx
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This setting purely affects the way the MFC dlls are used with your applicaiton. They are either linked statically, ie, they are built into the exe (like a .lib file) or they are not, in which case the machine your exe is going to run on had better have the latest MFC dlls installed. (See Microsofts ludicrously named 'side by side' installation for more info on what an utter joke this has become. Yes, with manifests, and versions. Dll hell just became manidest hell...).
Anyway, enough slaging off the people at Microsoft...
Your library is either a dll or a lib.
If it is a lib then you want to use static linking. Make sure the lib is in the link path, and make sure the lib is added to the projects link settings.
If it is a dll you want to use dynamic linking. Even with a dll there is a tiny little lib file, make sure that is in your link path and that it is added to your projects link settings. And deploy the dll with your exe.
==============================
Nothing to say.
modified on Thursday, September 15, 2011 6:12 AM
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For Visual Studio, under the project properties go to the Linker tab. Under general, you can modify the Additional Library directories field if the *.lib file created by your other project is not in a standard directory and not in the same directory as the project. Then under Input, you add the lib file under Additional Dependencies (you probably already see the standard files, such as kernel32.lib, user32.lib, etc. added).
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Yes, I know. That is what I said to the OP. 
==============================
Nothing to say.
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I hate it when people reply to me when they meant that for OP. 
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I thought it cleaner (view-wise) to respond to you, to make it clear it was a small specific addition to what you said. If the OP read your answer, he/she (I figured) would probably read my answer right after it.
Unfortunately, the alert system at CP only decides to inform you. But in this case, it doesn't matter because my post was only an addition to your post for if the OP hadn't seen it yet.
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OK, so next time reply to the OP and say "in addition to what xxx said..."
That way you are seen as giving credit, rather than copying someone else, and the right person gets your post.
==============================
Nothing to say.
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I should think that, assuming I was not doing this by mistake, one would see this as giving credit.
If I had posted in parallel without referring to the other person's post, now that would indeed look like copying.
And I already explained why I thought it was acceptable that the OP did not receive a notification.
All in all, I don't see why everybody is getting all round up about this. Technically, I was doing it right ... But apparently, I am in heavy violation of CP forum etiquette (specifically CP forum, as other forums I have been active on do not go into a /rage mode over such as I've seen happen here :P )
Maybe it's the extra spam? Then again, one can hardly post on a board and then complain about notifications.
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These settings won't affect your problem. Check that your library is correctly exporting the relevant entry points and that the linker is able to find it when you build your project.
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This is the most likely cause... at least for the first error... +5 (+10 if I could  )
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Thanks but you're too kind. Errors such as this are basic stuff that the average developer should be well able to diagnose; especially if they are being paid for their work.
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You're very welcome and very true about the being paid part...
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Your use of MFC can be either way. But the restriction is that for both projects, the use must be the same. So even though you have a static library project, it may use or include MFC either statically or dynamically. Regardless of which of those two settings you apply to your static library project, you must apply the same setting to your second project that is linking with your static library.
Chris Meech
I am Canadian. [heard in a local bar]
In theory there is no difference between theory and practice. In practice there is. [Yogi Berra]
posting about Crystal Reports here is like discussing gay marriage on a catholic church’s website.[Nishant Sivakumar]
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Hello Friends
I want to know about lay out diagram of an application.My Application is having One main Toolbar with Some buttons and have four Other toolbar having around 20 controls in those toolbars.
For each Toolbar ,I created a separate dll. Main toolbar Will consist of main.Now,i want to know that how can i use four other toolbar dlls in main so that
1)if i want to remove one of four toolbar i remove that dll and it doesnt affect whole application.
2)And I want to initialize those four toolbars only one time and want to use their values in between four toolbars and main toolbars,like static.
3)want to consider memory and other speed issues.
Thanks In Advance.
Regards
Yogesh
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So that's getting on for 100 controls, which is far more than the average user can handle. You may want to consider:
1. Looking at the Windows Ribbon Bar - see Michael Dunn's Ribbon series[^].
2. Redesigning your application to reduce the number of tools required in toolbars.
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Hello,Thanks for Reply.
i am using Ribbon Toolbar for this but i want to know that How do i link all these dlls.
Which Architecture should I follow?
Regards
Yogesh
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yogeshs wrote: Which Architecture should I follow?
The architecture of the Ribbon Toolbar, as referred to in the link in my previous message.
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Hi,
I am using CRichCtrl for displaying text. I have data in columns.
It is coming is correct format. But If line is having a space in starting then It is not displaying the space because of that my formatting is not coming correct.
If data is
10
9
it is displaying like
10
9
I can no not use Right aligned becuase my other data will get spoiled.
Please suggest.
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john5632 wrote: I am using CRichCtrl
I assume you actually mean CRichEditCtrl[^]. In order to line up columns you need to use a fixed width font for that field; see the difference as follows (I use the character i in order to demonstrate the width clearly:
10
i9 - variable width
10
i9 - fixed width
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