C# Discussion Boards - CodeProject

Xiaoming Qian14-Jun-07 15:16

14-Jun-07 15:16

Hi everybody.I have problems when calling dll.
Here is the Dll function definition(from the vander's document):

<br />
__int16 __stdcall MW_GetDBRecord(HANDLE icdev, __int16 fsid,<br />
      __int16 rec_size, char *buf, int *rlen)<br />
Input parameters: 	<br />
icdev:		device handle <br />
fsid:			selected table NO. <br />
rec_size:		a record size space.<br />
Output parameters :<br />
Buf: 		return entire record data (you need give buf enough space );<br />
Rlen:		length of data .<br />

And here is my code:

<br />
[DllImport("mwhandset")]<br />
public static extern Int16 MW_GetDBRecord(IntPtr icdev,Int16 fsid,<br />
      Int16 rec_size,ref string buff,ref int rlen);<br />
<br />
...<br />
<br />
private void button3_Click(object sender, System.EventArgs e)<br />
{<br />
  ...<br />
  int rlen = 0;<br />
  string buff;<br />
  buff = "                                       ";//the length is enough<br />
  MW_GetDBRecord(m_icdev,0,16,buff,ref rlen);<br />
}<br />
<br />

When calling MW_GetDBRecord it raise "System.NullReferenceException: Object not set to an instance".I'm sure the function has completed on the device,

because rlen=16(the record size) when the exception raised.So I think it is caused by type incompatibility,most likely the buff parameter.What type should I

use corresponding to "char *buf"? Or it is caused by any other reason?
Can anyone help me? Any idea will be appropriate.

Re: A qustion on Dll Call

Tarakeshwar Reddy14-Jun-07 17:03

Tarakeshwar Reddy

14-Jun-07 17:03

This has to be

Xiaoming Qian wrote:
[DllImport("mwhandset")]
public static extern Int16 MW_GetDBRecord(IntPtr icdev,Int16 fsid,
Int16 rec_size,ref string buff,ref int rlen);

Like this:

public static extern int MW_GetDBRecord(IntPtr icdev, int fsid,<br />
int rec_size, [Out] byte[] buf, int bufSize);<br />

And this has to be

Xiaoming Qian wrote:
MW_GetDBRecord(m_icdev,0,16,buff,ref rlen);

this

int size = 256; //what ever you want it to be
byte[] buf = new byte[size];

MW_GetDBRecord(m_icdev, 0, 16, buf, size);

I suggest you read these articles.[^]

Tarakeshwar Reddy
MCP, CCIE Q(R&S)

There are two kinds of people, those who do the work and those who take the credit. Try to be in the first group; there is less competition there. - Indira Gandhi

Re: A qustion on Dll Call

Xiaoming Qian14-Jun-07 20:41

Xiaoming Qian

14-Jun-07 20:41

Thank you, it works.
Big Grin | :-D

how to put a Button Image into an array?

Khoramdin14-Jun-07 14:38

Khoramdin

14-Jun-07 14:38

Hello everyone,

I use the following code to place an image "temp.jpeg" into an array and then write the array into a remote database.

                int FileSize;<br />
                byte[] ImageArray;<br />
                FileStream fs;<br />
                int iBytesRead;<br />
<br />
                // 1.<br />
                OpenFileName = "temp.jpeg";<br />
                <br />
                // 2. By using FileStream object, fill the byte array. <br />
                fs = new FileStream(OpenFileName, FileMode.Open, FileAccess.Read, FileShare.Read);<br />
                FileSize = Convert.ToInt32(fs.Length);<br />
<br />
                // 3. Declare an array of that size.<br />
                ImageArray = new byte[FileSize];<br />
                iBytesRead = fs.Read(ImageArray, 0, FileSize);<br />
                fs.Close();

I was wonder what I should do if the image is not a file such as "temp.jpeg" and it is the image displayed in a Button?

Can someone be kind enough to help me out on this one?

Thank you very much and have a great day.

Khoramdin

Re: how to put a Button Image into an array?

alexey _N14-Jun-07 18:44

alexey _N

14-Jun-07 18:44

You can save the image displayed in a Button to temporary file, and after that read from this file. Or you can save this image to stream, and then read it's data to array.

My english is not so good. Please, correct my errors.
Best regards, Alexey.

Convert Large Icons into Small????

classNoob14-Jun-07 13:29

classNoob

14-Jun-07 13:29

Does anyone know if it is at all possible to take an ImageList of large icons, resize them, and dump the smaller images into another ImageList? I am trying to do this dynamically since I will not have any smaller versions of the icons available to me.

Using your own classes in methods.

jblouir14-Jun-07 12:32

jblouir

14-Jun-07 12:32

I am pretty sure I have some sort of syntax problem here but I can't get my head around it, dont see anything wrong.

I have made a class called cRoom, I create several room objects from this and shove them in an ArrayList.

class cRoom
{
//variables left out for better viewing

public cRoom(//insert loads of strings and ints here)
{
}

// All the public get/sets go here, again left out for better viewing.
}

//at some point in my Main() program ill call a method called North
//rActive is a cRoom object, arrRoomList is an array of cRooms

rActive = North(rActive,arrRoomList)

// The method for North

public static cRoom North(cRoom activeRoom, ArrayList roomList)
{
if (activeRoom.NORTH != 0)
{
foreach (cRoom room in roomList)
{
if (room.RID == activeRoom.NORTH)
{
return room;
}
}
}
else
{
Console.WriteLine("I can't go that way.");
return activeRoom;
}
}

Anyway when the code is compiled I get two errors.

Inconsistent accesibility: return type ....cRoom is less accessible than method.....North
Inconsistent accesibility: parameter type...cRoom is less accessible than method....North

Thanks in advance. =)

Re: Using your own classes in methods.

Guffa14-Jun-07 12:55

Guffa

14-Jun-07 12:55

The cRoom class is private and the North method is public. That means that the method is available outside of the surrounding class, but it's unusable as it's impossible to create the cRoom object that is needed for calling it.

Just make the method private also.

---
single minded; short sighted; long gone;

Re: Using your own classes in methods.

jblouir14-Jun-07 13:05

jblouir

14-Jun-07 13:05

Thanks! Worked a charm.

Its decided to throw another one at me now.

'Adventure.Program.North(Adventure.Program.cRoom, System.Collections.ArrayList)': not all code paths return a value

which I am guessing has something to do with the ArrayList

im only returning the cRoom object

Re: Using your own classes in methods.

jblouir14-Jun-07 13:26

jblouir

14-Jun-07 13:26

Not all code paths return a value...

What code paths is it refering to?

code paths in a class or in the method?

Well...

jblouir14-Jun-07 13:31

jblouir

14-Jun-07 13:31

the variables in my class cRoom are private

but they all have public get/set returns

I dont see what I am missing

Re: Well...

jblouir14-Jun-07 13:37

jblouir

14-Jun-07 13:37

eh woops I think I just figured it out

edit:

eh nope, still the same thing

each room has a number associated to their north south east and west exits

if its 0 there is no exit that direction

otherwise its 101 or 102 etc.

so if activeRoom.NORTH != 0 then its going to == 102 or another number

then I take that number and shove it into int RID

then I search each cRoom in the arraylist for that value

and if it finds it then it takes the rooms value and drops it into the activeRoom and its returned

Re: Well...

jblouir14-Jun-07 13:47

jblouir

14-Jun-07 13:47

Ok I solved the problem...

For some reason it didnt like the fact that I had the return activeRoom; in the follow position

foreach (cRoom room in roomList)
{
if (room.RID == RID)
{
activeRoom = room;
return activeRoom;
}
}

So I moved it here

foreach (cRoom room in roomList)
{
if (room.RID == RID)
{
activeRoom = room;
}
}
return activeRoom;

and it worked fine

I guess I cant have a return value in a foreach loop

Thanks for your help. =)

Re: Well...

Christian Graus14-Jun-07 13:52

Christian Graus

14-Jun-07 13:52

jblouir wrote:
I guess I cant have a return value in a foreach loop

You can, although it's good form to only have one return, at the end of a method.

Christian Graus - Microsoft MVP - C++
Metal Musings - Rex and my new metal blog
"I am working on a project that will convert a FORTRAN code to corresponding C++ code.I am not aware of FORTRAN syntax" ( spotted in the C++/CLI forum )

Re: Using your own classes in methods.

Guffa14-Jun-07 13:30

Guffa

14-Jun-07 13:30

jblouir wrote:
im only returning the cRoom object

Not always, that's what the error message is saying.

Look at the logic in the method. If activeRoom.NORTH is non-zero but not found in the list, the method doesn't return anything.

---
single minded; short sighted; long gone;

Re: Using your own classes in methods.

Rudolf Jan15-Jun-07 0:27

Rudolf Jan

15-Jun-07 0:27

If you declare a method that returns a value, you must make sure that all places where you may exit the function will return a value of that type. Example:

public int MyFunc()
{
if (errorcondition)
  {
  return 2;
  }
else
  {
  // no returns
  ...
  }
// here must be a return value
return 0;
}
}

multi list problem [modified]

bolhassanim@bellsouth.net14-Jun-07 10:34

bolhassanim@bellsouth.net

14-Jun-07 10:34

I am trying to use the same class to populate the second list in my second class, but the list will have the last set of values. The only way that it work if I instantiate multiple classes, please help, why I can not use only instantiating my classes once D'Oh! | :doh:

. Here are the codes

<b><pre>First file</pre></b>
<code>
using System;
using System.Collections.Generic;
using System.Text;

namespace xpop
{
class Program
{
static void Main(string[] args)
{
_xobj xobj = new _xobj();
popxmlobj(xobj);
}
// Does work but have to instatiate the calss object twice need to re- use the calss object
static void popxmlobj1(_xobj xobj)
{
_AllValue aValue1 = new _AllValue();

aValue1.valueName = "VAL1Name";
aValue1.Values.Add("Val1");
xobj.fieldName = "FieldName1";
xobj.fieldValues.Add(aValue1);

_AllValue aValue2 = new _AllValue();
aValue2.valueName = "VAL2Name";
aValue2.Values.Add("Val2");
xobj.fieldValues.Add(aValue2);
}
// Works if I use this method
static void popxmlobj(_xobj xobj)
{
for (int i = 0; i < 2; i++)
{
if (i == 0)
{
_AllValue aValue1 = new _AllValue();

aValue1.valueName = "VAL1Name";
aValue1.Values.Add("Val1");
xobj.fieldName = "FieldName1";

xobj.fieldValues.Add(aValue1);
}

if (i == 1)
{
_AllValue aValue1 = new _AllValue();

aValue1.valueName = "VAL2Name";
aValue1.Values.Add("Val2");

xobj.fieldValues.Add(aValue1);
}
}
}
}
}
</code>

<b>pre>Second file</pre></b>
<code>
using System;
using System.Collections.Generic;
using System.Text;

namespace xpop
{
public class _xobj
{
public string fieldName;
public List<_AllValue> fieldValues = new List<_AllValue>();
}

public class _AllValue
{
public string valueName;
public List<string> Values = new List<string>();
}
}
</code>

mohsenb55

-- modified at 10:07 Friday 15th June, 2007

Re: multi list problem

Christian Graus14-Jun-07 11:47

Christian Graus

14-Jun-07 11:47

mohsenb55 wrote:
static void popxmlobj1(_xobj xobj)
{
_AllValue aValue1 = new _AllValue();

aValue1.valueName = "VAL1Name";
aValue1.Values.Add("Val1");
xobj.fieldName = "FieldName1";

_AllValue aValue2 = new _AllValue();
xobj.fieldValues.Add(aValue2);

aValue2.valueName = "VAL2Name";
aValue2.Values.Add("Val2");

xobj.fieldValues.Add(aValue2);
}

This code adds aValue2 to xobj twice, I assume this is not right ?

Re: multi list problem

bolhassanim@bellsouth.net14-Jun-07 18:19

bolhassanim@bellsouth.net

14-Jun-07 18:19

Hi Christian,

aValue2 is actually aValue1 I mistyped it. The problem is that I like to instantiate the _AllValue class only one time and re-use the same object multiple times. In the above code to get it to work, the _AllValue class is instantiated twice aValue1 and aValue2. I want to be able to re-use the same object, let's say _AllValue aValue = new _AllValue(); and re-use as many times I want too and not have to intantiate _AllValue twice.

Thanks for the response

Delimiters - Is there a simple way

haz1314-Jun-07 10:19

haz13

14-Jun-07 10:19

I have a text file of the following format

"apple","orange","pear" etc

I have tried both char and string seperators but can't think of a way grab the data cleanly without including a " or , . I either end up with "apple" "orange" "pear" or "apple orange pear"

The code I have been using.

private static char[] charSeperator = new char[] { ',' };
private static string[] strSeperator = new string[] {"\",\""};

strArray = strLine.Split(charSeperator);
strArray = strLine.Split(strSeperator,StringSplitOptions.None);

Is there a simple way of grabing apple orange and pear from the text file, without having to do further data cleaning?

Thanks in advance for any help you can offer

Haz

Re: Delimiters - Is there a simple way

Paul Conrad14-Jun-07 10:31

Paul Conrad

14-Jun-07 10:31

You may want to try regular expressions...

"too much daily WTF for someone..." - Anton Afanasyev

Re: Delimiters - Is there a simple way

haz1314-Jun-07 10:39

haz13

14-Jun-07 10:39

Sorry Paul what do you mean by regular expressions? I'm only fairly new to this c#