Re: FileSystemObject in VB returns the wrong value when used from .NET - C# Discussion Boards

Re: FileSystemObject in VB returns the wrong value when used from .NET

11-Jan-04 16:46

I have constructed a COM object in VB6 that exposes various methods to handle custom files. This object works very well when I use it from a normal VB6 project, but when I use it through COM Interop in a C# application a strange error appear:

Inside one of the functions in the COM dll I use the FileExists method on a FileSystemObject. When this method is called from the C# code FileExists returns false, even though the file exists. When the same method is called with the same filename as parameter in VB everything works.

Anyone who have any idea of what I am doing wrong?

Rickard

Heath Stewart12-Jan-04 1:52

Re: FileSystemObject in VB returns the wrong value when used from .NET

12-Jan-04 1:52

You should debug both projects (start debugging the C#/.NET client in VS.NET and then start your VS6 and attach to the process) and see what string is getting passed to the COM object. The behavior shouldn't really change from caller to caller except when parameters differ. A different value might be getting marshaled to your COM object than what you're passing from your C# code.

My initial thought is that there is a Unicode vs. ASCII problem with string encodings. .NET stores Unicode strings internally and your VB6 control might not be expecting that. See the VB6 StrConv function for information pertaining to converting from/to Unicode strings.

-----BEGIN GEEK CODE BLOCK-----
Version: 3.21
GCS/G/MU d- s: a- C++++ UL@ P++(+++) L+(--) E--- W+++ N++ o+ K? w++++ O- M(+) V? PS-- PE Y++ PGP++ t++@ 5 X+++ R+@ tv+ b(-)>b++ DI++++ D+ G e++>+++ h---* r+++ y+++
-----END GEEK CODE BLOCK-----

RickardB12-Jan-04 13:41

Re: FileSystemObject in VB returns the wrong value when used from .NET

12-Jan-04 13:41

Good tip! I had actually start to think in those lines!

Thanks!

Rickard

RickardB12-Jan-04 17:26

Re: FileSystemObject in VB returns the wrong value when used from .NET

12-Jan-04 17:26

The COM dll is written in Visual Basic. Could you describe to me how I can attach to this process and debug it using VB6? I can't find any attach to process in my VB6..

Rickard

RickardB12-Jan-04 20:47

Re: FileSystemObject in VB returns the wrong value when used from .NET

12-Jan-04 20:47

I solved it!

Found a good article on this URL

http://support.microsoft.com/?kbid=811658

Rickard

RickardB14-Jan-04 0:00

Re: FileSystemObject in VB returns the wrong value when used from .NET

14-Jan-04 0:00

Hi,

I have now debugged my application and the string seems to be alright, but it
still doesn´t work, or actually it worked for a while, but suddenly
the same error occured again.

Could this be some kind of access problem?

Could it make a difference in I run the com in process or out of process?

Rickard

Heath Stewart14-Jan-04 3:31

Re: FileSystemObject in VB returns the wrong value when used from .NET

14-Jan-04 3:31

No, it would be an access problem if one client could access it via your COM component but another client couldn't, unless they were running with different credentials (something you have to manually do through several steps). This sounds more like a marshaling problem as I mentioned before.

Your COM component can only run as an out-of-process server if it is a stand-alone executable (.exe), so that's not even a valid case.

Since it worked before, you're obviously doing something right. Since it changed, you should figure out what changed. Two compiled applications don't magically change. If this is a marshaling problem, make sure you understand that Windows 9X/ME (Windows) use ASCII while Windows NT/2000/XP(/future versions of Windows) (Windows NT) use Unicode. I can't remember exactly how VB handles strings, but you can code your .NET applications to P/Invoke methods using either ASCII or Unicode depending on the OS type, which it will automatically do for you (see CharSet.Auto). I don't remember exactly how VB deals with the different OSes. Find out how that works and make sure your .NET application marshals the string accordingly appropriately on either of the Windows OS system type.

Rocky Moore12-Jan-04 11:02

Rocky Moore

12-Jan-04 11:02

One other quick thought, not likely but you might check permissions and the creditials being used.

Rocky <><
www.HintsAndTips.com

Re: FileSystemObject in VB returns the wrong value when used from .NET

RickardB12-Jan-04 13:37

Re: FileSystemObject in VB returns the wrong value when used from .NET

12-Jan-04 13:37

Thanks, will keep this in mind.

Rickard

RickardB14-Jan-04 0:01

Re: .NET Rebar Control Error

14-Jan-04 0:01

.NET Rebar Control Error

David M. Kean11-Jan-04 15:54

David M. Kean

11-Jan-04 15:54

I have created my own Rebar Control and I am having issues on Windows 2000 machines.

When creating the handle it throws an Win32Exception with the error "Invalid window class name". It works fine on Windows XP machines.

The following is my CreateHandle method and CreateParams property. Any ideas?

protected override void CreateHandle()
{
if (!RecreatingHandle)
{
// Initialize Cool Bar Common Control
INITCOMMONCONTROLSEX initCommonControls = new INITCOMMONCONTROLSEX(); // I set Size field in constructor
initCommonControls.Flags = InitCommonClasses.COOL_CLASSES | InitCommonClasses.BAR_CLASSES;
SafeInterop.InitCommonControlsEx(initCommonControls);
}

base.CreateHandle(); // <-- Exception thrown here
}

protected override CreateParams CreateParams
{
[SecurityPermission(SecurityAction.LinkDemand, Flags=SecurityPermissionFlag.UnmanagedCode)]
get
{
CreateParams createParams = base.CreateParams;
createParams.ClassName = Interop.REBARCLASSNAME;

createParams.Style |= (int)(CommonControlStyles.NORESIZE | CommonControlStyles.NODIVIDER | CommonControlStyles.NOPARENTALIGN);

if (_Borders)
{
createParams.Style |= (int)RebarStyles.BANDBORDERS;
createParams.Style |= (int)(RebarStyles.VARHEIGHT | RebarStyles.AUTOSIZE);

return createParams;
}
}
}

Heath Stewart12-Jan-04 1:36

Re: .NET Rebar Control Error

12-Jan-04 1:36

You must make sure that your window class is registered using RegisterClass(Ex) API. InitCommonControls does this for classes defined in the common controls library, but any custom classes must be registered by you.

David M. Kean12-Jan-04 10:49

David M. Kean

12-Jan-04 10:49

I found out what is was. The INITCOMMONCONTROLSEX structure had the size and flags fields the wrong way, so the call to InitCommonControlsEx was failing. It's just weird that it worked fine Windows XP, sometimes is really bad for developing on, because it hides errors.

Mix Events

Heroz11-Jan-04 12:35

Heroz

11-Jan-04 12:35

Hey guys!
How can i mix events in C#?
I want make a function what only runs when the mouse button is pressed, and the mouse's moving.

MS Visual Studio.NET 2003
C#

Re: Mix Events

Colin Angus Mackay11-Jan-04 14:05

Colin Angus Mackay

11-Jan-04 14:05

Here's an idea: How about in the OnMouseDown set a flag to say the mouse is pressed, in the OnMouseUp reset the flag back to its initial state. Then in the OnMouseMove event you can check the status of the flag to determine if the button is pressed or not.

--Colin Mackay--

EuroCPian Spring 2004 Get Together[^]

How to simulate map c++ collection in c#

Rostrox11-Jan-04 11:49

Rostrox

11-Jan-04 11:49

Hello:

Look at the next C++ code:

1) Defining map
const int cols=15;
struct stTot {
string strDesc;
double fTots[cols];
} myTot;
map<int, stTot> mpLis;
map<int, stTot>::iterator it;

2) Loading map
int iCnt = 0;
myTot.strDesc = (LPCTSTR)some_string;
for (int v=0; j<cols; myTot.fTots[j++]=0);
mpLis[iCnt] = myTot;

3) Extracting data from map
it = mpLis.find(some_value)
for (f=0;f<cols;f++)
{
monto_n3[f] += monto_pf[f];
(*it).second.fTots[f] = monto_pf[f];
}

In spite of some things that could be optimized in this code, it looks “elegant and powerful”, question is: How can I do this in C# so it looks elegant and powerful also?
I know that C# has System.Collections.Hashtable but it does not seem to solve the previous code. Who can surprise me?

Many, many thanks if you answer me.

Best regards

Eduardo Gironas.

Re: How to simulate map c++ collection in c#

Heath Stewart11-Jan-04 11:54

Re: How to simulate map c++ collection in c#

11-Jan-04 11:54

Please do not re-post - continue the original thread.

What you're code is using is an enumerator. The Hashtable and other collections support this, too. See Hashtable.GetEnumerator, which returns an IDictionaryEnumerator. Other collections and lists (those that implement IEnumerable, which ICollection and IList do, so any of their implements do as well) return an IEnumerable.

If the Hashtable doesn't work for you, there are plenty of other collections and lists in System.Collections and System.Collections.Specialized that can. If you don't like the provided implementations, write your own ICollection, IList, or IDictionary implementation.

Rostrox11-Jan-04 12:13

Rostrox

11-Jan-04 12:13

Heath:
Many thanks for your answer.
The real problem is with the structure:
struct stTot {
string strDesc;
double fTots[cols];
} myTot;
I cannot replicate this in C#. I tried many alternatives but I do not really know how to use it (the structure) during the Hashtable loading and recovery of data. A non elegant solution is to join every field that is in the mentioned structure into an string variable and then split them during recovery.
Best regards

Re: How to simulate map c++ collection in c#

Heath Stewart11-Jan-04 12:22

11-Jan-04 12:22

public struct myTot
{
  public string strDesc;
  public double[] fTots;
}

As you can see, there are a few limitations due to either the language specifications or the .NET Framework.

As far as putting this in a collection or Hashtable, the default, non-specialized implementations take objects as both keys and values. Ever class or value type (which a struct is) derives from System.Object, so you can put a struct in a Hashtable:

myTot tot = new myTot();
tot.strDesc = "blah";
tot.fTots = new double[] {1.2, 3.4};
Hashtable t = new Hashtable();
t["key1"] = tot;
// ...
Console.WriteLine(((myTot)t["key1"]).strDesc);

Read the documentation for the classes in System.Collections about enumerations, collections, lists, and dictionaries. For instance, to enumerate through all the values of a dictionary using the keys, you could do the following:

// Use "t" from example above for hashtable.
IEnumerator e = t.Keys.GetEnumerator();
while (e.MoveNext())
{
  Console.WriteLine("{0}: {1}", e.Current, t[e.Current]);
}

You could also use the foreach keyword for a shortcut:

foreach (object key in t.Keys)
{
  Console.WriteLine("{0}: {1}", key, t[key]);
}

startup parameters?

Leon Radley11-Jan-04 10:35

Leon Radley

11-Jan-04 10:35

I have a windows form application that i'd like to be able to send startup parameters to tell it what settings file to load say:

myApp.exe /settings.xml

how would a do this?

EuroCPian Spring 2004 Get Together[^]

Colin Angus Mackay11-Jan-04 10:57

Colin Angus Mackay

11-Jan-04 10:57

There are two ways:

1. You receive the startup parameters through an array of string objects passed into the static Main() method.

2. You can access the startup paramters from anywhere in your application using Environment.CommandLine property (this will give you the whole command line as one string) or the Environment.GetCommandLineArgs() method which will split the command line up into its component arguments. See MSDN for more details on how to use these methods/properties.

I hope this helps,
Colin.

--Colin Mackay--

Heath Stewart11-Jan-04 11:32

11-Jan-04 11:32

Colin's right about command-line parameters, but if you want to pass settings specifically, you should use a .config file (in the form, yourappname.exe.config) and use either the <appSettings> section or make your own using IConfigurationSectionHandler. Use that as a keyword to search the CodeProject articles for a slew of examples. This is a better way since if is directly supported by the CLR and the class library, as well as maintains all settings for an application (even ones that you're application doesn't use directly, like assembly bindings) in one file.

Nick Parker11-Jan-04 11:38

Nick Parker

11-Jan-04 11:38

Heath Stewart wrote:
Use that as a keyword to search the CodeProject articles for a slew of examples.

Or he could just use mine: An extension for a Configuration Settings class in .NET[^] Poke tongue | ;-P

- Nick Parker
My Blog

Heath Stewart11-Jan-04 11:42