C# Discussion Boards - CodeProject

DllImport quick quetion please? [modified]

mktrend26-Apr-08 11:18

26-Apr-08 11:18

I must use the functions in an unmanaged DLL. The function prototype is as follows:

extern "C" double __stdcall AvgEntryPrice(LPSTR instrument, LPSTR account)
My best effort is below but it's not working, can I get some help on this please, thanks.

// PInvokeTest.cs<br />
using System;<br />
using System.Runtime.InteropServices;<br />
<br />
class PlatformInvokeTest<br />
{<br />
    [DllImport("NtDirect.dll")]<br />
    public static extern double AvgEntryPrice(string c, string c);<br />
<br />
    [DllImport("NtDirect.dll")]<br />
    internal static extern int _flushall();<br />
<br />
    public static void Main()<br />
    {<br />
        AvgEntryPrice("ES08", "Sim101");<br />
        _flushall();<br />
    }<br />
}

modified on Saturday, April 26, 2008 5:25 PM

Re: DllImport quick quetion please?

Christian Graus26-Apr-08 11:22

Christian Graus

26-Apr-08 11:22

How do you know it's not working, if the dll never returns anything to you ?

I assume this is not a Windows dll. www.pinvoke.net has lots of signatures for windows dlls. They have some info too, it may still help. But, this looks OK to me.

Christian Graus

Please read this if you don't understand the answer I've given you

"also I don't think "TranslateOneToTwoBillion OneHundredAndFortySevenMillion FourHundredAndEightyThreeThousand SixHundredAndFortySeven()" is a very good choice for a function name" - SpacixOne ( offering help to someone who really needed it ) ( spaces added for the benefit of people running at < 1280x1024 )

Re: DllImport quick quetion please?

mktrend26-Apr-08 11:28

mktrend

26-Apr-08 11:28

Hi, thanks for your response.
1-I get the "The parameter name 'c' is a duplicate'
which is from the line where it says ....AvgEntryPrice(string c, string c);....

p.s. edited
OK,I took care of this problem! it now reads the following am going to chec it agais now.

AvgEntryPrice(string instrument, string account);

Re: DllImport quick quetion please?

Christian Graus26-Apr-08 11:34

Christian Graus

26-Apr-08 11:34

Oh - that self explanatory then. You can't have two parameters with the same name. Sorry, that's just so obvious that I missed it, I was looking for a p/invoke problem, not a general coding one.

Re: DllImport quick quetion please?

mktrend26-Apr-08 11:37

mktrend

26-Apr-08 11:37

I don't get any build error after correcting the above problem but when running the .exe I get the following error:

Failed to initialize COM library (0x80010106).

Re: DllImport quick quetion please?

Christian Graus26-Apr-08 11:43

Christian Graus

26-Apr-08 11:43

OK, now your code works, but you have a problem with this dll. If it's a COM dll, you should import it into your project, not use p/invoke. Otherwise, read the docs for the dll, to work out why you're calling it incorrectly.

Re: DllImport quick quetion please?

mktrend26-Apr-08 11:53

mktrend

26-Apr-08 11:53

in the DOS win, it gives the following message. BTW line 15 is ..AvgEntryPrice("ES08", "Sim101");
I also put the DLL in the same dir as the .exe

AvgEntryPrice("ES08", "Sim101");

Unhandled Exception: System.AccessViolationException: Attempted to read or write
protected memory. This is often an indication that other memory is corrupt.
at PlatformInvokeTest.AvgEntryPrice(String instrument, String account)
at PlatformInvokeTest.Main() in C:\Documents and Settings\k\My Documents\C# C
odes\DLL Methods\ConsoleApplication2\ConsoleApplication2\Program.cs:line 15

Re: DllImport quick quetion please?

mktrend27-Apr-08 1:43

mktrend

27-Apr-08 1:43

Hi Christian,
thanks your response.
1- this is not a COM dll, should I still import the dll? if yes, then how? the dll cannot be referenced!
2- the dll has no docs, the only thing about it is that it uses the _stdcall convention and in my MATLAB procedure that works successfully using the loadlibrary function, I must include the _stdcall in the prototype also I had to create a header file for it too.

thanks

Re: DllImport quick quetion please?

mktrend26-Apr-08 12:24

mktrend

26-Apr-08 12:24

I hope maybe this info might help to put me on the right track.
I have no problem using the DLL via MATLAB for which I made a header file .h and then just use the loadlibrary and the callib and it gets the job done!
What is the equivalent way of doing the same in C#?
thanks

Re: DllImport quick quetion please?

mktrend27-Apr-08 1:37

mktrend

27-Apr-08 1:37

This is a modified version of my code, after correcting a couple of minor problems. It builds fine but running it causes the same error!
I have the below questions:
1- the dll uses _stdcall, should I include that anywhere in my code?
2- how can I insert the setdllpath in my code to make sure the path to the dll and it's dependents are all included in the search?
3- why is the error seeing the dll as a COM?
thanks

using System;<br />
using System.Runtime.InteropServices;<br />
<br />
class PlatformInvokeTest<br />
{<br />
    [DllImport("NtDirect.dll")]<br />
    public static extern double MarketData(string instrument, int type);<br />
<br />
    [DllImport("NtDirect.dll")]<br />
    internal static extern int _flushall();<br />
<br />
    public static void Main()<br />
        <br />
    {<br />
        string instrument = "ER2 06-08";<br />
        int type = 0;<br />
        MarketData(instrument, type);<br />
        _flushall();<br />
    }<br />
}

Conversion Problem....

AliNajjar26-Apr-08 10:49

AliNajjar

26-Apr-08 10:49

Hi everybody.
I want to know if there is an equivalant in C# for the "Variant" type in Delphi.
Any ideas. A tiny example would be great.
thank in advance

Re: Conversion Problem....

Christian Graus26-Apr-08 11:23

Christian Graus

26-Apr-08 11:23

No, there's no variant that I know of, if variant is the same in Delphi as it is in VB. A variant means it can be anything, but you define what it is, right ? Easy to write one. Or you can use object and use the gettype function to work out what type is stored.

Why do you need it ?

Re: Conversion Problem....

AliNajjar26-Apr-08 11:38

AliNajjar

26-Apr-08 11:38

Thanks for reply..

In Delphi, I use Variant type to declare these variables (ComplexNum : Variant) . But I don't know how
to do so in C#...

What I need this for is to deal with complex numbers (((and arrays of it)))).
So...
In Delphi,
I use Variant type to declare these variables (ComplexNum : Variant) OR (ComplexNumArray : array of Variant).
But I don't know how to do so in C#
Any Ideas???
Thanks so much>>>

Re: Conversion Problem....

Christian Graus26-Apr-08 11:42

Christian Graus

26-Apr-08 11:42

Looks[^] like there's a number of complex number libraries for C#.

Re: Conversion Problem....

AliNajjar26-Apr-08 11:46

AliNajjar

26-Apr-08 11:46

I know about those Libs and I alrady have some, BUT,
All of them doesn't have a method to deal with the complex number as a String for an example >> Smile | :)

thanks for patience>>>> Smile | :)

Any Ideas..

C# fax problem

Member 386320926-Apr-08 10:26

Member 3863209

26-Apr-08 10:26

hi
I have a new project with C# that can send and recieve a fax
I want to use faxcomlib.dll to send a fax
but I donot know how to recieve a fax and retrieve a fax status
anyone can help me please ?

Re: C# fax problem

Christian Graus26-Apr-08 11:26

Christian Graus

26-Apr-08 11:26

I'd suggest reading the article I link to in my sig. Then, try typing C# fax into google. OR type fax into the search on code project. Either way, you will quickly find this[^].

Re: C# fax problem

Member 386320926-Apr-08 21:46

Member 3863209

26-Apr-08 21:46

This article you give , just send fax not recive fax and not give fax status,
can you help me about this issue??

Automatically print PDF file generated by website

Brad Wick26-Apr-08 9:45

Brad Wick

26-Apr-08 9:45

I have a program which takes the full screen that just allows users access to our website. We have one place where they click a button which generates a PDF file that they need to print.

Currently I can open and display the PDF file in the browser window, but since the application is the TopMost window always the print dialog is not visible (this happens when you click the print icon in Acrobat which is embeded into the window).

How can I either automatically print the PDF file and not even display it, or make the print window ontop of my form?

How to Check if my Printer is Connected

mostafa_h26-Apr-08 7:50

mostafa_h

26-Apr-08 7:50

hi i want to check if my printer is connected to my pc and show my model (using c# code ).
plz help me .
thx in advance

s_mostafa_h

Re: How to Check if my Printer is Connected

Spacix One26-Apr-08 8:06

Spacix One

26-Apr-08 8:06

Alright, I'll help you with your post as requested:

mostafa_h wrote:

Currently I'm trying to check if a printer is connected to my computer.
I am using this code:
//the code you've tried
and I was getting this error message:
The error message you was getting goes here

After I get this to work, I would like to know if there is a way to detect the printer's model number or type of printer.
I looked on google and found this Url to example[^] but it is using native API's and that I don't know how to call in C#

s_mostafa_h

-Spacix
All your skynet questions[^] belong to solved

Re: How to Check if my Printer is Connected

mostafa_h26-Apr-08 8:40

mostafa_h

26-Apr-08 8:40

what's ur mean ? where did u find and copy this and put to my message ?
i don't remember to post this before ,
sorry !

s_mostafa_h

Re: How to Check if my Printer is Connected

Mustafa Ismail Mustafa26-Apr-08 8:29

Mustafa Ismail Mustafa

26-Apr-08 8:29

Have you tried google? I got this on the very first hit.

Clickety[^]

Clickety 2[^]

"Every time Lotus Notes starts up, somewhere a puppy, a kitten, a lamb, and a baby seal are killed. Lotus Notes is a conspiracy by the forces of Satan to drive us over the brink into madness. The CRC-32 for each file in the installation includes the numbers 666." Gary Wheeler

"You're an idiot." John Simmons, THE Outlaw programmer

"I realised that all of my best anecdotes started with "So there we were, pissed". Pete O'Hanlon

Re: How to Check if my Printer is Connected

mostafa_h26-Apr-08 8:47

mostafa_h

26-Apr-08 8:47

thanx a lot !

s_mostafa_h

Re: How to Check if my Printer is Connected

Mustafa Ismail Mustafa26-Apr-08 8:53

Mustafa Ismail Mustafa

26-Apr-08 8:53

You're welcome, but please in the future spend a good 10-20 minutes googling your query and reading the results. If that doesn't work, post to the forums.

Till the next time Smile | :)

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