C# Discussion Boards - CodeProject

Re: Removing duplicates in an array

8-Aug-03 10:21

is there any way to remove duplicates in an array or an arraylist? i see there are no functions, but i'm having a hard time wrapping my head around making an function which will do this.

Krishnan111119778-Aug-03 13:53

Krishnan11111977

8-Aug-03 13:53

Why don't u try using another class like Hashtable or DictionaryEntry struct..
they take a key-value pair..and do not allow duplicate keys..
also the read/access time of these is O(1)

Re: Removing duplicates in an array

James T. Johnson8-Aug-03 14:30

James T. Johnson

8-Aug-03 14:30

Krishnan11111977 wrote:
also the read/access time of these is O(1)

Thats not quite correct, it is realistically close to O(1) but under bad circumstances it can be O(n).

Unfortunately, I've seen examples where people override GetHashCode and have it return a constant value. This would be one of those 'bad circumstances' because the Hashtable would have to search through all of the keys that returned the same hash code (ie all of them) to find the correct key.

Usually this is done when someone doesn't know how they should override GetHashCode when they override Equals. The contract is that if two objects are considered equal then the hash code must be the same. Another part of the contract is that an object must return the same hash code over its lifetime. Because of those two details, it can be tricky for someone to correctly override GetHashCode while also overriding Equals.

I didn't intend to write this much, honest! Blush | :O

[edit]I do agree, using a Hashtable should be a quick way of determining if you have a duplicate item.[/edit]

James

"My words but a whisper -- your deafness a SHOUT.
I may make you feel but I can't make you think." - Thick as a Brick, Jethro Tull 1972

"Removing Events" and -=

flipdoubt8-Aug-03 9:19

flipdoubt

8-Aug-03 9:19

I've designed a class (not a control) that has some custom events. Then I want to clear the class of it's current values, refill the values, and then re-register to the events, as different clients listen to different events. But how do I clear the event queue (or whatever the += syntax adds events to) of the previous events? I haven't seen any good examples of -= syntax nor can I find any in the MSDN docs.

Any ideas?

Re: "Removing Events" and -=

flipdoubt8-Aug-03 9:32

flipdoubt

8-Aug-03 9:32

The following seems to work:

myClass.MyEvent = null;

Don't you love it when you answer your own questions? Wink | ;)

How to set an Extended Style?

Alvaro Mendez8-Aug-03 7:46

Alvaro Mendez

8-Aug-03 7:46

Here's how I do it in VC6:

- Load a dialog resource in the resource editor
- Add an edit box
- Open the Properties box
- Click on the Extended Styles tab
- Click on the Modal Frame checkbox

How is this done for C# using SharpDevelop or VS.NET?

I wouldn't mind doing it programmatically. I just couldn't find an ExtendedStyles property for the textbox control.

Thanks in advance!
Alvaro

If you want to get to the top, prepare to kiss a lot of bottom. -- despair.com

Stephane Rodriguez.8-Aug-03 19:46

Stephane Rodriguez.

8-Aug-03 19:46

override the CreateParams property, and hardcode the implementation for "get".

FYI, the default implementation is :

protected override CreateParams get_CreateParams()
{ 
 CreateParams params1;
 IWin32Window window1;
 Form form1;
 Form form2;
 params1 = base.CreateParams;
 if (this.TopLevel)
 {
  params1.Style = (params1.Style & -134217729);
 
 }
 if (this.TopLevel && (this.formState[Form.FormStateAllowLayered] != null))
 {
   params1.ExStyle = (params1.ExStyle | 524288);
 }
 window1 = ((IWin32Window) base.Properties.GetObject(Form.PropDialogOwner));
 if (window1 != null)
 {
  params1.Parent = window1.Handle;
 }
 this.FillInCreateParamsBorderStyles(params1);
 this.FillInCreateParamsWindowState(params1);
 this.FillInCreateParamsBorderIcons(params1);
 if (this.formState[Form.FormStateTaskBar] != null)
 {
  params1.ExStyle = (params1.ExStyle | 262144);
 }
 if (this.IsMdiChild)
 {
  if (base.Visible && ((this.WindowState == 2) || (this.WindowState == 0)))
 {
  form1 = ((Form) base.Properties.GetObject(Form.PropFormMdiParent));
 form2 = form1.ActiveMdiChild;
 if ((form2 != null) && (form2.WindowState == 2))
 {
  params1.Style = (params1.Style | 16777216);
  this.formState[Form.FormStateWindowState] = 2;
  base.SetState(65536, 1);
 }
 
}
 if (this.formState[Form.FormStateMdiChildMax] != null)
 {
  params1.Style = (params1.Style | 16777216);
 }
 params1.ExStyle = (params1.ExStyle | 64);
 
}
 if (this.TopLevel || this.IsMdiChild)
 {
  this.FillInCreateParamsStartPosition(params1);
  if ((params1.Style & 268435456) != 0)
  {
   this.formState[Form.FormStateShowWindowOnCreate] = 1;
   params1.Style = (params1.Style & -268435457);
  }
 
}
  if (this.IsRestrictedWindow)
  {
   params1.Caption = this.RestrictedWindowText(params1.Caption);
  }
 return params1; 
}

Reflector is your friend!

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igor19609-Aug-03 21:54

igor1960

9-Aug-03 21:54

Yes, just to change window style (1 check in VC IDE) you now have no choice but to wrap somebodies control and overload the method.
Great!...

"...Ability to type is not enough to become a Programmer. Unless you type in VB. But then again you have to type really fast..."
Me

Stephane Rodriguez.10-Aug-03 2:32

Stephane Rodriguez.

10-Aug-03 2:32

In its current .NET 1.x implementation, winforms is crap. I hope that .NET 2.0 brings a brand new stuff to play with.

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reading attributes in AssemblyInfo.cs

igor196010-Aug-03 13:57

igor1960

10-Aug-03 13:57

I hope that .NET 2.0 brings a brand new stuff to play with.

I doubt. But we will see.

"...Ability to type is not enough to become a Programmer. Unless you type in VB. But then again you have to type really fast..."
Me

zuhx8-Aug-03 7:23

zuhx

8-Aug-03 7:23

How can I read the pre-existing attributes that are found in the AssemblyInfo.cs file?

Re: reading attributes in AssemblyInfo.cs

flipdoubt8-Aug-03 9:26

flipdoubt

8-Aug-03 9:26

I use the following methods to fill the About Box. There may be better ways to do it, as this was some of the first .NET code I wrote, but it works.

public string GetCopyright( Assembly a )
{
Type tCopyRight = Type.GetType( "System.Reflection.AssemblyCopyrightAttribute" );
Object[] ao = a.GetCustomAttributes( tCopyRight, false );

if( ao != null && ao.Length == 1 )
{
AssemblyCopyrightAttribute attribute = ao[0] as AssemblyCopyrightAttribute;
if( attribute != null )
return attribute.Copyright;
}
}

public string GetProduct( Assembly a )
{
Type tProduct = Type.GetType( "System.Reflection.AssemblyProductAttribute" );
Object[] ao = a.GetCustomAttributes( tProduct, false );

if( ao != null && ao.Length == 1 )
{
AssemblyProductAttribute attribute = ao[0] as AssemblyProductAttribute;
if( attribute != null )
return attribute.Product;
}
}

public string GetTitle( Assembly a )
{
Type tTitle = Type.GetType( "System.Reflection.AssemblyTitleAttribute" );
Object[] ao = a.GetCustomAttributes( tTitle, false );

if( ao != null && ao.Length == 1 )
{
AssemblyTitleAttribute attribute = ao[0] as AssemblyTitleAttribute;
if( attribute != null )
return attribute.Title;
}
}

public string GetVersion( Assembly a )
{
return a.GetName().Version.ToString();
}

Re: reading attributes in AssemblyInfo.cs

zuhx8-Aug-03 11:25

zuhx

8-Aug-03 11:25

Thanks for the reply. I tried something similiar to what you have posted, but nothing is returned for the title. Even thought I have an entry in the Assembly title attribute AssemblyInfo.cs file. Any idea why this might happen ?

explode string

mikemilano8-Aug-03 6:51

8-Aug-03 6:51

i would like to explode a string into an array, .. but not each character into an array.

in php the code would be:

<br />
$string = "Here is my string";<br />
$array = explode(" ",$string);<br />

$array[0] would be "Here"
$array[1] would be "is"

i need to explode a string in c#, but with a more complicated explode parameter. is there any functions i'm missing here that would do this?

Radoslav Bielik8-Aug-03 7:34

Radoslav Bielik

8-Aug-03 7:34

I think that the String.Split method is what you're looking for. You can even use several distinct delimiter characters:

<br />
string strSource="Here is my string, hello world!";<br />
string[] strArray=strSource.Split(new Char[] {' ', ','});<br />
foreach(string str in strArray) Console.WriteLine(str);<br />

Hope this helps!

Rado

mikemilano8-Aug-03 11:44

8-Aug-03 11:44

I was having trouble with the string.Split() method. I thought It returned a character array .. but I could be wrong.

I ended up using Regex.Split() to accomplish this.

Thanks for the help.

Csharp™8-Aug-03 12:43

Csharp™

8-Aug-03 12:43

you can use Split like this...
C#:

<br><br><font color="blue">private</font> <font color="blue">void</font> button1_Click(<font color="blue">object</font> sender, System.EventArgs e)
<br>{
<br><font color="darkgreen">    <font color="blue">string</font></font>[] str="Here is my string".Split(' ');<font color="darkgreen">
<br>    <font color="blue">for</font></font>(<font color="darkgreen"><font color="blue">int</font> </font>x=str.GetLowerBound(0);x!=str.GetUpperBound(0)+1;x++)<font color="darkgreen">
<br></font>        {
<br>            MessageBox.Show(str[x]);
<br>	  }
<br>}
<br>

Radoslav Bielik8-Aug-03 12:45

Radoslav Bielik

8-Aug-03 12:45

mikemilano wrote:
I was having trouble with the string.Split() method. I thought It returned a character array .. but I could be wrong.

Well, it takes a character array containing delimiter characters as an input parameter and returns a String array, this means that the example from my previous post would return an array containing 6 items, i.e.

strArray[0] - "Here"
strArray[1] - "is"
strArray[2] - "my"
strArray[3] - "string"
strArray[4] - "hello"
strArray[5] - "world!"

(as we have specified space and comma as delimiter characters.)

Rado

mikemilano8-Aug-03 13:16