C# Discussion Boards - CodeProject

yyf22-Mar-04 10:10

22-Mar-04 10:10

Hi, everyone

1. When I call a function imported from a VC6 dll, it returns 42949672970 when it is supposed to return -1. Anyone knows why?

2. There's another function in this VC6 dll like this loginDlg(LPCTSTR Name, long NameLength). This function will return the login name by the first parameter, 2nd parameter is tell the function how long the buffer is.
How to import and use this kind of functions properly?

Thanks in advance.

Re: from VC6 dll

Heath Stewart22-Mar-04 11:47

Heath Stewart

22-Mar-04 11:47

Looks like the address of a return value is being returned. How are you declaring the native function to be P/Invoked?

Microsoft MVP, Visual C#
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Re: from VC6 dll

yyf23-Mar-04 3:10

yyf

23-Mar-04 3:10

Here is how the function declare in the VC6 dll head file

#ifndef LONG<br />
typedef long LONG;              /* 32 bit */<br />
#endif<br />
<br />
LONG _stdcall SelectChildProjects<br />
(<br />
   LONG lProjectId               /* i  Number of parent project */<br />
);

Here is how I declare the function in my .Net code

<br />
[DllImport("dcli.dll", EntryPoint="SelectChildProjects")]<br />
public static extern long SelectChildProjects(long lProjectId);

Thanks.

Re: from VC6 dll

Heath Stewart23-Mar-04 3:13

Heath Stewart

23-Mar-04 3:13

A LONG (long) in C++ is a 32-bit integer. A long (Int64) is a 64-bit integer. You're marshaling is all wrong which might explain why you're getting extra data from overflow. You should declare it as:

[DllImport("dcli.dll")]
public static extern int SelectChildProjects(int lProjectId);

Notice I also dropped the EntryPoint property, which you only need in cases where your declared method differs in name from the entry point exported by the native DLL.

Microsoft MVP, Visual C#
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Re: from VC6 dll

yyf23-Mar-04 4:01

yyf

23-Mar-04 4:01

Thank you very much! It works prefectly now.

Loop through a Datagrid

Anonymous22-Mar-04 9:55

Anonymous

22-Mar-04 9:55

Hi,

Is it possible to loop through a datagrid? For eg.

for (int i=0;i

Re: Loop through a Datagrid

Heath Stewart22-Mar-04 11:46

Heath Stewart

22-Mar-04 11:46

Loop through the underlying data source, not the DataGrid itself.

Microsoft MVP, Visual C#
My Articles

Re: Loop through a Datagrid

Anonymous22-Mar-04 11:51

Anonymous

22-Mar-04 11:51

Actually the source is a dummy query which has no underlying table or any such database connection. The query exists only because I wanted to populate the datagrid. Its the data grid I want to manipulate actually. Or if there is another way to populate the rows and cols of a datagrid into an array that would be fine. Do you know if I can do that? I could the loop through the array and retreive the records I want.

Thanks
Al

Re: Loop through a Datagrid

Heath Stewart22-Mar-04 11:57

Heath Stewart

22-Mar-04 11:57

Read the documentation for the DataGrid.DataSource property in the .NET Framework SDK. It just has to be an object that implements IList or IListSource, so you could use an array or a collection as well. This is true for the rest of the data-bindable controls using a CurrencyManager.

Microsoft MVP, Visual C#
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Re: Loop through a Datagrid

Ruchi Gupta22-Mar-04 12:11

Ruchi Gupta

22-Mar-04 12:11

A liitel addition to what Heath Stewart said....

grid1.DataSource = dataTable;

CurrencyManager cm = (CurrencyManager)this.BindingContext[grid1.DataSource, grid1.DataMember];

DataView dv = (DataView)cm.List;

for(int i = 0; i < dv.Count ; i++)
{
//do what u want
}

Ruchi

Re: Loop through a Datagrid

Heath Stewart23-Mar-04 2:46

Heath Stewart

23-Mar-04 2:46

Whether you're binding to a DataSet or DataTable, it's a lot easier to just get the table you want to enumerate and create a DataView over that table using:

DataView dv = new DataView(dataTable1);
// Or
DataView dv = dataTable1.DefaultView;

Microsoft MVP, Visual C#
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Property questions

gkrish522-Mar-04 9:01

gkrish5

22-Mar-04 9:01

What is a limitation on a property ? I think none of the below are but am i correct ?

Choice 1
Properties cannot be inherited.
Choice 2
Properties do not allow for lazy initialization.
Choice 3
Properties cannot be defined as write-only.
Choice 4
Properties cannot return unsigned value types.
Choice 5
Properties cannot be used as method parameters.

II
(I feel "abstract" is right. Can anyone confirm ?
What modifier do you use in a base class to require any derived class to implement a property?
Choice 1
sealed
Choice 2
virtual
Choice 3
protected
Choice 4
abstract
Choice 5
mustoverride

Thanks

GK

Re: Property questions

CWIZO22-Mar-04 9:20

CWIZO

22-Mar-04 9:20

Properties do not allow for lazy initialization.

I never heard of lazy initialization.

Properties cannot be inherited.: Property itself of corse it cannot be inheriated, but as a part of a class there is no probblem.

As for second abstract is correct.

// btw: May I ask from where these questions are?

Q:What does the derived class in C# tell to it's parent?
A:All your base are belong to us!

Re: Property questions

leppie22-Mar-04 9:27

leppie

22-Mar-04 9:27

CWIZO wrote:
I never heard of lazy initialization.

Then I suggest you look at ROTOR's codebase. Its full of it. EG

object foo = null;
public object Foo
{
  get {return (foo == null) ? (foo = new object()) : foo;}
}

CWIZO wrote:
Properties cannot be inherited.: Property itself of corse it cannot be inheriated, but as a part of a class there is no probblem.
Now only a VB person would think that way! Laugh | :laugh:

^{top secret}

Re: Property questions

CWIZO22-Mar-04 9:31

CWIZO

22-Mar-04 9:31

I am not a VB person (never programmed there).
I never heard one would inheriate only the property in C#.

I am confused (maybe this would be becouse of my bad english?)

Q:What does the derived class in C# tell to it's parent?
A:All your base are belong to us!

Re: Property questions

gkrish522-Mar-04 11:20

gkrish5

22-Mar-04 11:20

I found these as part of a quiz somewhere

Re: Property questions

leppie22-Mar-04 9:22

leppie

22-Mar-04 9:22

1. none, i concur with u
2. again i agree with u, mustoverride is a VB6 keyword. I reckon this catches all of them wannabe VB.NET web monkeys Laugh | :laugh:

^{top secret}

Does this control exists???!!!

Andretux22-Mar-04 8:16

Andretux

22-Mar-04 8:16

Hello friends, how are you?

My name is André, I´m brazilian, so my english is not so good, but I hope that you understand. Wink | ;)

I need a Grid Control (or a ListView) that I can put 2 lines in the same cell....

If you could, please, see the next link, so this have a System Screen Picture that have the control I need. The control is these that contains tha products list: the product name in the first line, and the price and others informations in the second line (for each product).

http://www.acsn.com.br/Imagens/Frente%20de%20Caixa/Ampliadas/vendas%20ampliado.jpg

If you could help, I will be glad...

Thanks...

André

André

Re: Does this control exists???!!!

Heath Stewart22-Mar-04 9:05

Heath Stewart

22-Mar-04 9:05

Search CodeProject for "ListView". You should find several examples for custom drawing with the ListView.

Microsoft MVP, Visual C#
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Find Reverse Color

Werdna22-Mar-04 7:07

Werdna

22-Mar-04 7:07

How can I find a reverse of a color?
Actually what I need is a color that will be readable on another background color.
For example if the background is white, the color would be black, if the background is dark green, the color would be white.
I tried using GetBrightness() of color to determine whether to use white or black, but that doesn't seem to work.

Re: Find Reverse Color

leppie22-Mar-04 8:53

leppie

22-Mar-04 8:53

I recall reading a trick that mite work (not sure if it on works for 8 bit colors), but i forgot now D'Oh! | :doh:

(has to do with an XOR with -1 or just using the complement of an int, a color is just an int).

But be inventive, try this:

A2 = 256 - A1;//now this would be dumb
R2 = 255 - R1;
G2 = 255 - G1;
B2 = 255 - B1;

Mite work, let me know, im interested in what works Smile | :)

[edit] this works pretty good [edit]

^{top secret}

How Can I control Host IE.

flywithu22-Mar-04 6:36

flywithu

22-Mar-04 6:36

When I make Active-x on C#. and It's host on IE.
ex.
<object id="a" width="700" height="700" classid="up3.dll#up3.Form1" iewastext="">

It work good. but I want , I control Host IE.
How I can get Host IE COOKIE, Control Location ? and etc.

IN C++, Get the Host IE Pointer, BUT C#, I don't know.

Tell Me how can i do?

thankyou.

http://flywithu.net

Re: How Can I control Host IE.

Heath Stewart22-Mar-04 9:00

Heath Stewart

22-Mar-04 9:00

The control location you can get through various properties of the current AppDomain (see AppDomain.CurrentDomain) or get the Assembly reference for your type and check various properties like Assembly.Location.

If you want to reference to the IWebBrowser2 interface for the host, you should make a property of that type (or just a simple object property) and pass that via script, which means you should expose the property through a defined class interface. I'm not aware of any simple means of querying for the host interface from a .NET control hosted in this manner (and this is a subject I did a lot of research on back in 1.0 beta days).

Microsoft MVP, Visual C#
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Save File Dialog/Open File Dialog in DataGrid

Anonymous22-Mar-04 6:11

Anonymous

22-Mar-04 6:11

Does anyone know if it is possible to implement a Save File Dialog and a Open File Dialog in a DataGrid Control in C#?

Thanks
Alex

Re: Save File Dialog/Open File Dialog in DataGrid

Dave Kreskowiak22-Mar-04 8:26

Dave Kreskowiak

22-Mar-04 8:26

Anonymous wrote:
implement a Save File Dialog and a Open File Dialog in a DataGrid Control

Implement one IN a Datagrid Control? No, it's not...

But if you talking about exporting the data in the control to a file, you would have to either serialize the data out to a binary or XML file on the click of a button or menu item maybe, it's up to you, or you could write your own export/import code easily enough.

RageInTheMachine9532

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