Indexers - C# Discussion Boards

Displaying a form from en existing form

7-May-08 11:56

A dictionary maps one type to another type. Either type can be a class or struct, so you can store all the values you want in a class or struct and map to instances of it.

Christian Graus

Please read this if you don't understand the answer I've given you

"also I don't think "TranslateOneToTwoBillion OneHundredAndFortySevenMillion FourHundredAndEightyThreeThousand SixHundredAndFortySeven()" is a very good choice for a function name" - SpacixOne ( offering help to someone who really needed it ) ( spaces added for the benefit of people running at < 1280x1024 )

Berlus5-May-08 21:35

Berlus

5-May-08 21:35

Hello,

I wrote a liitle program that displays a form with a button.
Once the button is pressed the program goes over the elemnts of some collection.

I would like to dispaly this elements on diffrent form, that would function as a simplified logger, on top of the existing form.

How can i do this ? must it be on a diffrent thread ? some code snippet would be great.

Thanks,
Berlus

Re: Displaying a form from en existing form

Abhijit Jana5-May-08 21:55

Abhijit Jana

5-May-08 21:55

your prolem is not clear from me. can you be more specific?
Thanks

Best Regards
-----------------
Abhijit Jana
"Success is Journey it's not a destination"

Re: Displaying a form from en existing form

Christian Graus5-May-08 22:00

5-May-08 22:00

A second form would be on the same thread, just design it, and make an instance a member variable, then calling Show() would show it without stopping interaction with the main form. Show(this) would make it a proper child form. You can interact with it then via properties you expose, or use delegates to interact back to the main form

CheckBox in ListView

stancrm5-May-08 21:28

stancrm

5-May-08 21:28

Hello..

I have a ListView with CheckBoxes = TRUE. If I set FullRowSelect to TRUE, by DoubleClick (for example in Column 5) is the checkbox automatically set to TRUE or FALSE. How to avoid this ?

I want to use FullRowSelect (because of DoubleClick) but I don't want to change the state of CheckBox.
CheckBox state can only be changed, if user click on checkbox, not on "anywhere" in row.

Thx..

Re: CheckBox in ListView

Christian Graus5-May-08 22:09

WorkFlow Project In Visual Studio 2005

5-May-08 22:09

I assume you'd have to derive a class from teh control, handle the click and stop it from changing the state of the control if it's not in the right area.

Indexers

Steve Declerck5-May-08 20:44

Steve Declerck

5-May-08 20:44

Hi all,

I don't understand most of this "Indexer" code :

namespace UsingIndexers
{
class TestIndexers
{
private string[] MyStrings;

public TestIndexers()
{
MyStrings = new string[] { "This", "is", "an", "indexer", "test" };
}

// array like access
public string this[int index]
{
get
{
if (index < 0 || index >= MyStrings.Length)
{
throw new ArgumentOutOfRangeException();
}
return MyStrings[index];
}
set
{
if (index >= MyStrings.Length)
{
throw new ArgumentOutOfRangeException();
}
else
MyStrings[index] = value;
}
}

static void Main()
{
TestIndexers MyIndexer = new TestIndexers();

Console.WriteLine("index 1 is: {0}", MyIndexer[1]);
}
}
}

Especially I don't understand the use of indexers. Every individual element of MyStrings can be accessed through MyStrings[i]. WHy still additional code for indexing ?
And also this line of code is difficult for me :

public string this[int index]

What is the meaning of "this" ?

Any help is very much appreciated...
Many thanks in advance !!

Best regards, Steve

Re: Indexers

Vikram A Punathambekar5-May-08 20:59

Vikram A Punathambekar

5-May-08 20:59

Steve Declerck wrote:
Every individual element of MyStrings can be accessed through MyStrings[i]. WHy still additional code for indexing ?

But your data should be private. The indexer allows you to expose a public interface (don't confuse that with a C# interface) for your private data. Of course, you could do away with an indexer and use a GetXXX(int index) method, but indexers are elegant. You are not limited to integers; you can also use other types for the indexer.

Steve Declerck wrote:
public string this[int index]

What is the meaning of "this" ?

this is a keyword used to refer to the home object, i.e., the object on which the code is operating.

I don't mean to be condescending, but a good book will explain all of this in greater detail. I'd recommend Andrew Troelsen.

Cheers,
Vikram.

The hands that help are holier than the lips that pray.

Re: Indexers

Steve Declerck5-May-08 23:15

Steve Declerck

5-May-08 23:15

Hello Vikram,

Thank you very much for your fast reply ! I understand it now...

Thanks, Steve

Re: Indexers

PIEBALDconsult6-May-08 6:05

PIEBALDconsult

6-May-08 6:05

Yeah, what Vikram said.

Plus, the actual data needn't be stored in an array.

An indexer could be implemented with a database query.

The data needn't be stored anywhere at all; one could write a factorial method as an indexer:

private ulong
this
[
    ulong i
]
{
    get
    {
        for ( ulong j = i - 1 ; j > 1 ; j-- )
        {
            i *= j ;
        }

        return ( i ) ;
    }
}

(Though that's fairly silly.)

Thaer Hamael5-May-08 19:29

Thaer Hamael

5-May-08 19:29

hi all
i instaled in My PC Visual Studio 2005 and I Wount to use the WorkFlow Project , what it's need to enable the template workflow in Visual Studio 2005 .

if it need FramewWOrk 3.5 i instaled it but it is not enable .
what i can do to enable it .

thanks for all Rose | [Rose]

Thaer

John_Adams5-May-08 20:57

John_Adams

5-May-08 20:57

Hi Thaer,

If you are looking to use SharePoint WorkFlow template in VS2005 then I think the following article will be helpful to you.
http://weblog.vb-tech.com/nick/archive/2007/02/25/2207.aspx[^]

Hope this helps Smile | :)

Regards,
John Adams
ComponentOne LLC

Thaer Hamael6-May-08 1:20

Thaer Hamael

6-May-08 1:20

Thanks Mr John Adams
i instaled it . and it's Ok But the Desinger is Error
the Error Is :-

The designer could not be show for this file becouse none of the classes within it can be
designed .

what i can dot for this problem ?
Thanks Mr Rose | [Rose]

Thaer

Abhijit Jana5-May-08 22:06

Abhijit Jana

5-May-08 22:06

For VS 2005, After Installing Framework 3.0 you have to install WWF Extention .

Best Regards
-----------------
Abhijit Jana
"Success is Journey it's not a destination"

Abhijit Jana5-May-08 22:31

Abhijit Jana

5-May-08 22:31

install it from

http://www.microsoft.com/downloads/details.aspx?FamilyId=A2151993-991D-4F58-A707-5883FF4C1DC2&displaylang=en[^]

Best Regards
-----------------
Abhijit Jana
"Success is Journey it's not a destination"

Thaer Hamael6-May-08 1:19

Thaer Hamael

6-May-08 1:19

Thanks Mr Abhijit Jana
i instaled it . and it's Ok But the Desinger is Error
the Error Is :-

The designer could not be show for this file becouse none of the classes within it can be
designed .

what i can dot for this problem ?
Thanks Mr Rose | [Rose]

Thaer

Picturebox question

MarkB7775-May-08 19:29

MarkB777

5-May-08 19:29

Hi,

I'm playing around with picture boxes at the moment, and was wondering...

Is there a way to stop a PictureBox from redrawing itself, so that I can draw a shape over the top of it using the form's onPaint event?

Cheers,

Mark Brock

Click here to view my blog

Christian Graus5-May-08 20:07

5-May-08 20:07

Once you start to handle the paint event, you've moved past the picture box, which is here to help people add plain images easily

Yevgen Lisovenko5-May-08 20:16

Yevgen Lisovenko

5-May-08 20:16

Override OnPaint handler:

protected pverride void OnPaint(System.Windows.Forms.PaintEventArgs pe)<br />
{<br />
   base.OnPaint(pe);<br />
<br />
   // Add code to paint any you want:<br />
   ...<br />
}

Christian Graus5-May-08 22:00

5-May-08 22:00

Yes, but at this stage, it's kind of pointless, isn't it ?

Re: Prompt user for Input

MarkB7776-May-08 15:05

MarkB777

6-May-08 15:05

Yes, but try it, it still does not draw over the top of a picturebox, only behind it.

I think Christian is right tho, its kind of pointless. I just wanted to know if it was possible to stop the picturebox re-rendering itself.

Mark Brock

Click here to view my blog

Prompt user for Input

Thomas Toh5-May-08 19:04

Thomas Toh

5-May-08 19:04

// Make sure a duplicate file doesn’t exist. If it does, keep on appending an incremental numeric until it is unique
string sFilename = System.IO.Path.GetFileName(myFile.FileName);
string ans;
while (System.IO.File.Exists(Server.MapPath(sSavePath + sFilename)))
{
Console.Write("Do you want to overwrite? (Yes/No)");
ans = Console.ReadLine();
Console.WriteLine("");

}
lblOutput.Text = "File already existed. A duplicate file has been created";

the logic is upload file -> if file exists -> prompt for user input -> if yes -> overwrite -> if no prompt for user input for new file name

the code is not finished.. but am i on the right path??

Christian Graus5-May-08 19:09