A basic question: how to use a dll

[menghuihantang]

I am recently learning how to use those useful dlls coming with Windows. But the header part of the dll file is all confusing to me :headbang: , like this one:

uint32_t SystemParametersInfoW(int32_t uAction, int32_t uparam, CStr lpvParam, int32_t fuWinIni);

which is one method in user32.dll. Cannot even understand what those parameters are supposed to mean.

Anywhere I can search or figure out how to use these dlls? Appreciate it. :worship:

[Rolf Kalbermatter]

QUOTE(menghuihantang @ Dec 9 2007, 09:26 PM)

I am recently learning how to use those useful dlls coming with Windows. But the header part of the dll file is all confusing to me :headbang: , like this one:

uint32_t SystemParametersInfoW(int32_t uAction, int32_t uparam, CStr lpvParam, int32_t fuWinIni);

which is one method in user32.dll. Cannot even understand what those parameters are supposed to mean.

Anywhere I can search or figure out how to use these dlls? Appreciate it. :worship:

Yes, http://msdn.microsoft.com/' target="_blank">MSDN (Microsoft Developer Networks) is your friend for any Windows API question. If it's not there it is undocumented and that means any other information you can find on the net might be right or completely off the tracks.

As far as to your function prototype, where the heck did you get that from? It uses datatypes Microsoft never used so far and is also inherently wrong. The W suffix to the function indicates that it is a Widechar (16bit Unicode) function, but the third parameter is CStr, which is basically an 8 bit ANSI string. That simply can't be right.

TIP: When searching for a WinAPI function on MSDN, never use the function name with the A or W suffix. While those functions are exported with the W or A suffix, Microsoft considers them equal as far as documentation is concerned. Which one is used and pulled in gets decided during compilation, based on preprocessor settings. For LabVIEW you always want to use the A version since LabVIEW strings are 8 bit MBC strings.

For the general understanding of these things: Knowing a good bit of C will help very much. The DLL calling interface is inherently C based and so are all its terms and conventions. That means that the Call Library Node can't really make it in any other way either, as unfriendly that interface can look to a LabVIEW only programmer. And that means as tempting those API calls could seem to you, without learning some basic C knowledge first you are really in for a hard ride with lots of crashes when you go down that road.

Rolf Kalbermatter

[menghuihantang]

Thanks, Rolf, for taking the time to write that much for a rookie :thumbup:

If I am right, I think I read a book authored by the same name. I just couldn't find the book in the shelf. Are you that author?

[Rolf Kalbermatter]

QUOTE(menghuihantang @ Dec 10 2007, 01:31 PM)

Thanks, Rolf, for taking the time to write that much for a rookie :thumbup:

If I am right, I think I read a book authored by the same name. I just couldn't find the book in the shelf. Are you that author?

I've made quite a lot of responses to posts about external code in LabVIEW on LAVA, the NI Developer Exchange, Info-LabVIEW mailing list and the German cousin of LAVA, and also published some short articles about this topic on http://expressionflow.com/author/rolfk/' target="_blank">Expression Flow but I haven't written a book so far

Rolf Kalbermatter

[menghuihantang]

QUOTE(rolfk @ Dec 10 2007, 01:16 PM)

I've made quite a lot of responses to posts about external code in LabVIEW on LAVA, the NI Developer Exchange, Info-LabVIEW mailing list and the German cousin of LAVA, and also published some short articles about this topic on http://expressionflow.com/author/rolfk/' target="_blank">Expression Flow but I haven't written a book so far

Rolf Kalbermatter

Ok, found the name. It's Relf, who has a book on imaging stuffs.

Well, a book can be a collection of articles, a working progress I guess :thumbup:

[Rolf Kalbermatter]

QUOTE(menghuihantang @ Dec 10 2007, 05:32 PM)

Ok, found the name. It's Relf, who has a book on imaging stuffs.

Well, a book can be a collection of articles, a working progress I guess :thumbup:

That is our resident http://forums.lavag.org/crelf-m181.html' target="_blank">LAVA champion in number of posts. He has for anything and everything here on LAVA an answer, but sometimes it is tongue in cheek. But he seems to slow down recently. Probably due to his preparations for a travel back home to down under.

And his book on LabVIEW imaging is quite good.

Rolf Kalbermatter

[crelf]

QUOTE(rolfk @ Dec 11 2007, 04:56 PM)

That is our resident http://forums.lavag.org/crelf-m181.html' target="_blank">LAVA champion in number of posts. He has for anything and everything here on LAVA an answer, but sometimes it is tongue in cheek. But he seems to slow down recently. Probably due to his preparations for a travel back home to down under.

Actually, it's because I've been absolutely flat ou at work I've recently changed positions at V I Engineering, Inc - I'm now the Chief Software Architect, and I've been busy during the transition period. That said, my new position will afford me even more time to work on technical solutions, ergo bother you good people here at LAVA even more

PS: I'll be offline for a couple of week - as you suggested, I'm heading home and I'm *gulp* not even taking my laptop with me

[Rolf Kalbermatter]

QUOTE(crelf @ Dec 11 2007, 04:06 PM)

PS: I'll be offline for a couple of week - as you suggested, I'm heading home and I'm *gulp* not even taking my laptop with me

Could that be because of intervention by some other significant person?

Rolf Kalbermatter

[crelf]

QUOTE(rolfk @ Dec 12 2007, 06:51 PM)

Could that be because of intervention by some other significant person?

Yes, but in a very roundabout way - I pack very light when I travel, so she's taken the "opportunity" to fill my remaining luggage allowance (including that which I can carry) so there's no room for the laptop. That said, I'll have plenty to keep me busy on my vacation - friends, family, beer, lamb roasts, real beef sausages, cricket...