C# Discussion Boards - CodeProject

9-Apr-04 23:43

"C# and the .NET Platform" by Andrew Troelsen, Apress[^]

Is pretty good... IMHO.

Re: Suggested reading?

Jesse Squire10-Apr-04 4:18

Jesse Squire

10-Apr-04 4:18

I was very fond of Jesse Liberty's Programming C#[^].

--Jesse

porting this code to c#

Paolo Ponzano9-Apr-04 19:48

Paolo Ponzano

9-Apr-04 19:48

hi,
I'm porting a program made in C to C# and I get blocked at this point

<br />
long UpdateCRC (unsigned long CRC, const char *buffer, long count)<br />
{<br />
<br />
  if ( buffer && count )<br />
  {<br />
     do {<br />
       CRC = ((CRC >> 8) & 0xFFFFFF) ^ CRCTABLE[(unsigned char)( (CRC & 0xff) ^ *buffer++ )]; <br />
     } while(--count);<br />
      <br />
  }<br />
  return CRC;<br />
}<br />
}<br />

My question is.... C# does not suppot --count and *buffer++...... how to solve it? it's better to make a dll from my old program and to call functions losing portability or there's a workaround??

thanks in advance

Roger Alsing9-Apr-04 19:55

Roger Alsing

9-Apr-04 19:55

first you have to mark your method "unsafe" since it uses pointers..

unsafe long UpdateCRC (unsigned long CRC, const char *buffer, long count)

also , c# dont auto convert numbers into bools, so you have to do:

while(--count>0);

//Roger

Paolo Ponzano9-Apr-04 20:11

Paolo Ponzano

9-Apr-04 20:11

and for what concern *buffer++??
I find extremly hard to use pointer in C#... =)

thanks for having answered me so fast

Mike Dimmick10-Apr-04 3:59

Mike Dimmick

10-Apr-04 3:59

Normally you'd pass the buffer as a byte[] - you probably wouldn't even bother passing count as .NET arrays have the Length property. A non-literal translation would be:

public static uint UpdateCRC( uint CRC, byte[] buffer )
{
   for ( int i = 0; i < buffer.Length; ++i )
   {
      CRC = 
         ( CRC >> 8 ) & 0xFFFFFF ^
         CRCTABLE[ (byte)( CRC & 0xFF ) ^ buffer[i] ];
   }
   
   return CRC;
}

[EDIT] Forgot a cast [/EDIT]

Stability. What an interesting concept. -- Chris Maunder

Paolo Ponzano10-Apr-04 5:07

Paolo Ponzano

10-Apr-04 5:07

thanks a lot for your help!
Paolo

What should I do?

lajiyo9-Apr-04 19:39

lajiyo

9-Apr-04 19:39

Hi every one:
I want to get a picture from access.I try to do it in many way.
But I failed.Could you give me some addvices?
Best wishes

Re: What should I do?

Mikko Puonti9-Apr-04 23:26

9-Apr-04 23:26

Maybe An ASP.NET Application to View and Share Photos Online
[^] would be helpful?

Re: What should I do?

lajiyo11-Apr-04 15:16

lajiyo

11-Apr-04 15:16

Thank you:
But it is a sql database.
I want to do it in Access database.
could you help me?

Re: What should I do?

Mikko Puonti12-Apr-04 5:58

Problems Creating C# Plugin Support for my App

12-Apr-04 5:58

Don't remember how things are done in Access, but normally images are stored to BLOBs (SQL datatype). Try to look from Access documentation is there any help available from BLOB datatypes. I am also pretty sure that there is ready example somewhere for access also. Try to use some google Smile | :)

Defiant009-Apr-04 18:57

Defiant00

9-Apr-04 18:57

I've got an application that I'm writing that I want to use plugins with. I've looked through the plugin examples, and to the best of my knowledge have done the same (although in a slightly different fashion) as the examples.

Oh, and sorry about the lack of tabs...I can't seem to get the forum to display them...

My plugin interface:

// The terrain modifier plugin interface.

public interface ITerrainPlugin {
string Name{get;}

void ShowInterface();

void CalculateHeight(float[,] heights);
}

The test plugin (no actual meaningful code...):

// project created on 4/1/2004 at 12:58 PM
using System;

public class TerrainNoisePlugin : ITerrainPlugin {

public string Name {
get {
return "Deffie's Terrain Noise Plugin";
}
}

public void ShowInterface() {
System.Windows.Forms.MessageBox.Show("Interface? Ha! Not yet, bud Smile | :)

");
}

public void CalculateHeight(float[,] heights) {

}
}

And here's the code to load the plugins (each is located in App.StartupPath + "\\Plugins\\Terrain\\" and args contains the class name, which is the same as the dll file name minus the .dll):

try {
Type plugType = null;
Assembly asm = null;
asm = Assembly.LoadFrom(Application.StartupPath + "\\Plugins\\Terrain\\" + args + ".dll");
if (asm != null) {
plugType = asm.GetType(args);
} else {
MessageBox.Show("Assembly is null");
}
if (plugType != null) {
object instance = Activator.CreateInstance(plugType);
if (instance != null) {
MessageBox.Show("Instance isn't null...type is: " + instance.GetType());
} else {
MessageBox.Show("instance is null");
}
ITerrainPlugin plugin = (ITerrainPlugin)instance;
if (plugin == null) {
MessageBox.Show("plugin instance is null");
} else {
plugin.ShowInterface();
}
} else
MessageBox.Show("Type is null");
} catch (Exception eX) {
MessageBox.Show("Error: " + eX.Message, "Error");
}

It complains at this line:
ITerrainPlugin plugin = (ITerrainPlugin)instance;
With the complaint that this is not a valid cast.

Any ideas?

Aaron

leppie9-Apr-04 21:09

leppie

9-Apr-04 21:09

Defiant00 wrote:
MessageBox.Show("instance is null");
TerrainPluginInterface plugin = (TerrainPluginInterface)instance;

Need i say more? [edit] actually I think I read it wrong (why dont ppl use {}?), what does the previous message box say? [edit]

^{top secret}

Defiant0010-Apr-04 8:12

Defiant00

10-Apr-04 8:12

Sorry about the lack of {}'s, since it was just some extra code I stuck in there to try and figure out what was going on (and the fact that it's rather easy to read if the tabs would show up properly...)

Anyways, I went back through and added {}s...by the way, the instance is not null when I run this (which is what has me so puzzled).

Aaron

Mikko Puonti9-Apr-04 23:37

9-Apr-04 23:37

Could it be that you need to define "TerrainPluginInterface" in own dll. And share this DLL with "TerrainNoisePlugin" and your application code? (Or define "TerrainPluginInterface" in same dll with your application and use application's "TerrainPluginInterface" in your plugin code.) Where is "TerrainPluginInterface" coming to your application code?

(BTW: Normal naming convention for interfaces is "I<interface name="">". For example: "ITerrainPlugin". ... and yes people really should use those bracers. Code is not writen for computers, it is written for humans (except binary machine code).)

Defiant0010-Apr-04 8:20

Defiant00

10-Apr-04 8:20

Ah...I guess that's what I was missing there (at least I hope that's what it is). I'm looking back over the tutorials...yeah, guess I skipped a bit too much of the explanation in favor for the code.

Also, didn't know about the naming convention, thanks for that (I've changed it now). As far as using the braces...well, if the forums would show tabs (although I imagine there's a way that I just don't know of) then it would be nice and readable anyways...but oh well...

Anyways, thanks for the suggestions, I'll look into it and hopefully have it working shortly.

Aaron

**And as an update (if anyone cares :P ) that fixed it.**