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Hi all ,Forgive my bad english,please.
I'm new user in c#.I have one problem about struct and pointer.
I want to create c# API that call DLL file in c++ .
//DLL sample as below(c++):
struct TESTA
{
DWORD A;
WORD B;
WORD C;
BYTE D[16];
};
typedef TESTA* LPTESTA;
BOOL CBook::InitialButton(LPTESTA pInfo)
{
//statement
return true;
}
//C# code as below:
unsafe public class callDLL
{
[StructLayout(LayoutKind.Sequential)]
public struct TESTA
{
public int A;
public ushort B;
public ushort C;
[MarshalAs(UnmanagedType.ByValArray, SizeConst= 16)]
public byte[] D;
}
[DllImport("dllname.dll")]
unsafe public static extern bool InitialButton(void* pInfo);
}
public class Initialize_sequence
{
unsafe static void Main(string[] args)
{
callDLL.TESTA pInfo=new callDLL.TESTA();
Console.WriteLine(Marshal.SizeOf(pInfo));
callDLL.InitialButton(&pInfo); //error happen 
}
}
error message show "Can't get position and size of Mananged type"
Any one can provide idea for me ? Thanks.
hello ALL..^^
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Instead of using the "unsafe" keyword in C# and using void* in the extern function signature, try this:
<br />
public static extern bool InitialButton(ref TESTA pInfo);<br />
and in the call to the function you would just do
<br />
callDLL.InitialButton(ref pInfo);<br />
The marshaller should automatically treat this as a pointer.
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I modified it as your suggestion.
It is ok .
Thank you very much.
hello ALL..^^
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Hi,
I am having two windows application Client and Host and one class library Customer. Host application holds the instance of Customer class. Customer class contains one windows form. It exposes a method to show that form.
Client application connects to Host through Remoting and get the Customer class.
When I try to open that form through the proxy_object, the form is being shown but the controls are not painted and it is in a hanged state.
Can anybody help me on this.
Thanks in advance
Regards,
Sabari.
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You have to invoke the showing of the form so this is executed in the context of the main UI thread. Take a look at the Control.Invoke method.
www.troschuetz.de
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How do I enable tracing? I put a "#define TRACE" in my code and it still does not print:
#define TRACE
using System;
namespace ConsoleApplication1
{
class Class1
{
[STAThread]
static void Main(string[] args)
{
System.Diagnostics.Trace.WriteLine("testing trace");
}
}
}
thanx, amir
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Hey Kevin,
Thanx for the help. The example in your link pointed me in the right direction. It looks like you need this line: "<debug|trace>.Listeners.Add(new TextWriterTraceListener(Console.Out));"
it tells the output where to go. you can specify the console's output or a file.
Trace is enabled automatically by .NET. So here is a sample of how to enable and disable different modes of tracing using trace or boolean switches:
Trace.Listeners.Add(new TextWriterTraceListener(Console.Out));
BooleanSwitch boolSwitch = new BooleanSwitch("ABooleanSwitch",
"Demo bool Switch");
TraceSwitch traceSwitch = new TraceSwitch("ATraceSwitch",
"Demo trace switch");
// Set the switch values programmatically
boolSwitch.Enabled = false;
traceSwitch.Level = TraceLevel.Info;
Trace.WriteLineIf(boolSwitch.Enabled, "bool switch is enabled");
Trace.WriteLineIf(traceSwitch.TraceInfo, "traceSwitch.TraceInfo is enabled");
Trace.WriteLineIf(traceSwitch.TraceError, "traceSwitch.TraceError is enabled");
thanx, amir
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I have a solution with two projects in it, a Managed C++ project and a C# project which is using (dependant on) the Managed C++ project. Is there any way to "Staticlly Link" this Assembly into the C# EXE. I need to keep them as seperate project for source control reasons so I can't move the files into that project directly.
Anyone know how to do this?
Thanks!!!
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AFAIK you cannot. Even if you could move the source code in to one project it still won't work as the source code is in two different languages and you cannot mix languages in a single project.
"If a man empties his purse into his head, no man can take it away from him, for an investment in knowledge pays the best interest." -- Joseph E. O'Donnell
Can't manage to P/Invoke that Win32 API in .NET? Why not do interop the wiki way!
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Hi all, I'm relativily new to c#, and I was wondering if it was possible to pass a TextBox object to a constructor...
heres the deal, I'm making a namespace for another program I am making... This namespace was intended to do networking actions on my project. I wish to send the text box to the constructor so that I can display messages of connections to the server.
here is my namespace code:
<br />
<br />
sing System;<br />
using System.Net.Sockets;<br />
<br />
<br />
namespace Tito_Network<br />
{<br />
public class Listen<br />
{<br />
<br />
public Listen(TextBox one, TextBox two)
{<br />
TcpListener tcp = new TcpListener(2486);<br />
tcp.Start();<br />
<br />
one.Text +="Server Activated...\n";<br />
<br />
Socket soc_Client = tcp.AcceptSocket();<br />
<br />
try<br />
{<br />
if(soc_Client.Connected)<br />
{<br />
while(true)<br />
{<br />
one.Text +="Client connected from"+soc_Client.AddressFamily;<br />
<br />
}<br />
}<br />
}<br />
<br />
catch(Exception s)<br />
{<br />
MessageBox.Show(s);<br />
}<br />
}<br />
<br />
<br />
<br />
}<br />
<br />
}<br />
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try constructor as below
public Listen(System.Windows.Forms.TextBox one, System.Windows.Forms.TextBox two)
{
}
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no that didnt work, it created more errors O_o
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I am sorry, I am unable to find out any other reason. Though I am sure you can always pass TextBox in the constructor argument. Some one else may help you out to resolve the bug.
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You've not posted your error message, people will find it very difficult to help you without it.
However, try changing the following
sing System;<br />
using System.Net.Sockets;
to
using System;<br />
using System.Net.Sockets;<br />
using System.Windows.Forms;
The TextBox control is stored in the System.Windows.Forms namespace.
If this doesn't help then try posting the full error message.
Kev Pearman MCP
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Hi,
I have a very simple custom control (just a button with a bitmap
background). Sometimes when I add several of the controls to a form and run the app the last one or two controls appear to lose their properties and are redrawn blank at the top left of the form. I finally noticed that when this happens there's an item in the task list that says : "Duplicate declaration of member 'Font'", though the build is successful. The app runs fine (all controls in their proper place) and the .cs file is fine. It's just that the designer goes a little crazy.
I've found several posts about this (mostly the same message, but
sometimes with member 'Location' or 'Size'), but most people think it was just a problem with an early version of Visual Studio 2003. I've got the June 2004 version and don't have a clue what I can do to solve this. I'd appreciate any help! Especially if someone from MS could look up the error message. I tried msdn, but don't find it.
To attempt to recreate copy several of the same custom control onto a form. I can usually make the bug occur when I copy/paste 12-15 instances of the control.
Please help!
thanks,
Deanna
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I need to translate the following C++ code to C#
for (int i = 0; i < sizeof(mnX)/sizeof(float); i++)
{
mnX[i] = 0f;
}
where (in C#)
float[] mnX = new float[2];
Using this line as it is in C# results in a compile error which says that "sizeof" can be used only in an unsafe context.
I changed the line to the following:
for( int i = 0; i < System.Runtime.InteropServices.Marshal.SizeOf(mnX)/sizeof(float); i++ )
{ mnX[i] = 0f; }
which, of course, still results in the same error.
My question is this: when I tried to use
System.Runtime.InteropServices.Marshal.SizeOf(float), that resulted in a compile error as well.
I don't want to wrap this block of code with the *unsafe* keyword and then compile using /unsafe.
What would be my best option?
Thanks!
// Added 4:00PM PDT
I guess I could just replace sizeof(float) with 4. Still, just for the sake of knowing how, I'd like to know how to get around the problem. 
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If I understand your code correctly, really all you're trying to do is loop for each element in your array. In C#, the number of elements within an array is stored within the "Length" property. You could do something like this, then:
for(int i = 0; i < minX.Length; i++)
...
You could do it using sizeof, as you've already discovered, but I don't think there's a way around doing that without marking the code as unsafe.
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John, thanks for the reply. I was wondering if I could just use mnX.Length myself. It definitely seems more elegant.
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I am wanting to know what is the best way to fill a combo box from data in a database. Right now I am using an data adapter to fill a dataset that is set as the datasource for the combo box. This seams to work ok.
From reading about datasets and dataadapter it looks to me that using this method keeps the link to the database open. Is that true?
On another combo box I have in my program I use a dataset to read an xml file. Then I use a foreach loop to add the data to the combobox. It is a small list of 10 or so records. The only problem with this is that I haven't found a way to add a value to each item in the combo box.
Using the dataset I can set the display member and value member. Just wanted to know what everyone though about this.
I am also concerned about how much memory is taken up by the comboboxes and the datasets that fill them.
Please let me know what you think about this. I know it is a small thing I want to make sure I'm using the best method.
Thanks,
JefferyS 
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I almost always use a dataset for the for the combo box. I would imagine that most others here would agree that there is nothing wrong with using datasets for combo boxes.
Jefferys wrote:
From reading about datasets and dataadapter it looks to me that using this method keeps the link to the database open. Is that true?
If you are using the Fill method of a dataAdapter to fill your dataset, then you are usually in a disconnected state. The Adapter connects to the database for the query, and then disconnects when it is finished. If you are using a dbConnection object, and opening/closing the connection yourself, then it's possible that you might be leaving the connection open. Either way, it is safer to let the dataAdapter do the work for you.
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I have a listcontrol in report mode, and I want the text in a particular column to be right aligned. That is, I want to see the end all the time. I cannot find a way to do this, I thought I had, but all I am aligning is the header. Is there a way to align the contents of the column, or do I need to draw the column myself ? Can I draw just one column ?
Christian
I have drunk the cool-aid and found it wan and bitter. - Chris Maunder
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I usually just use the designer to set up my list controls and setup column/header properties (title, alignment, and size) at that time. I've never yet had an instance in the programs I've developed where I didn't know how I wanted data aligned/formatted at design time.
Now, one thing I've noticed in general about list controls is that it doesn't seem you can right-align the FIRST column in a list control, but I believe that's a global truth about list controls, and not something specific to WinForms.
If at all possible, I would really recommend doing it through the designer. If it's not possible, I'd still recommend doing one through the designer and then look at the code that is generated and compare it with what you're doing. If you can't figure it out still, post some code that can be commented upon.
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Thanks for your advise. I've moved the column along from the first position, and set it up in the designer to be right aligned, all this does is right align the header ( which didn't happen even when I started ).
I'm adding the columns in the designer, and there's a drop down list for text alignment, which I set to 'Right'. This generates the same code I tried to add, something like thelist.Columns.TextAlignment = HorizontalTextAlignment.Right.
Thanks for your help.
Christian
I have drunk the cool-aid and found it wan and bitter. - Chris Maunder
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