Re: String implementation in .NET Framework - C# Discussion Boards

4-Nov-08 3:38

I have some legacy VB6 code which im converting over to C#, and it seems that strings were implemented very differently in old VB than in the Framework. I get vastly different results from the ported code than I do from an app written in VB and I was wondering if anyone could put their finger on the reason why?

here is the old VB code (pstrResponse is the input to the method):

For i = 1 To Len(pstrResponse)

      j = Asc(Mid(pstrResponse, i, 1))

      If j > 127 Then

         j = j - 128

         Mid(pstrResponse, i, 1) = Chr(j)

      End If

   Next i

Here is my ported C# (input is the input):

char[] charArray = input.ToCharArray();
int bit;
for (int i = 0; i < charArray.Length; i++)
{
    bit = (int)charArray[i];
    if (bit > 127)
    {
        bit -= 128;
        charArray[i] = (char)bit;
    }
}
return new string(charArray);

As you can see, simple code & easy to port but very different results. Any ideas people?

Ennis Ray Lynch, Jr.4-Nov-08 4:06

Ennis Ray Lynch, Jr.

4-Nov-08 4:06

.NET stores string in Unicode not Ascii and a char is 2 bytes not one I think? Which would mean the -=128 could have a different value in an integer data type?
I don't really know I am just speculating.

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J4amieC4-Nov-08 4:12

4-Nov-08 4:12

Ennis Ray Lynch, Jr. wrote:
Which would mean the -=128 could have a different value in an integer data type

Any idea what it could be?

Ennis Ray Lynch, Jr.4-Nov-08 4:18

Ennis Ray Lynch, Jr.

4-Nov-08 4:18

Maybe, Asc(Mid(pstrResponse, i, 1)) != (int)characters[i];

Try using the System.Text.AsciiEncoder to change the string by ascii bytes only first and see what happens?

J4amieC4-Nov-08 5:25

4-Nov-08 5:25

Thanks for the pointers. With your help ive managed to solve the problem, but strangly enough I thought id need to convert my input to ASCII using ASCIIEncoding.GetBytes. In actual fact I had to use DefaultEncoding.GetBytes to get the result I was expecting. Confused | :confused:

here's the working code now:

byte[] byteArray = Encoding.Default.GetBytes(input);

StringBuilder sb = new StringBuilder(byteArray.Length);
byte bit;
for (int i = 0; i < byteArray.Length; i++)
{
    bit = (byte)byteArray[i];
    if (bit > 127)
    {
        bit -= 128;
    }
    sb.Append((char)bit);
}
return sb.ToString();

Thanks again for your help.

DaveyM694-Nov-08 4:32

DaveyM69

4-Nov-08 4:32

Apparently this still exists in the Microsoft.VisualBasic namespace.

This is the Asc function after being run through reflector - it seems to work OK.

public static int Asc(char theChar)
{
    int num;
    int num2 = Convert.ToInt32(theChar);
    if (num2 < 0x80)
    {
        return num2;
    }
    try
    {
        byte[] buffer;
        Encoding fileIOEncoding = Encoding.Default;
        char[] chars = new char[] { theChar };
        if (fileIOEncoding.IsSingleByte)
        {
            buffer = new byte[1];
            int num3 = fileIOEncoding.GetBytes(chars, 0, 1, buffer,
            0);
            return buffer[0];
        }
        buffer = new byte[2];
        if (fileIOEncoding.GetBytes(chars, 0, 1, buffer, 0) == 1)
        {
            return buffer[0];
        }
        if (BitConverter.IsLittleEndian)
        {
            byte num4 = buffer[0];
            buffer[0] = buffer[1];
            buffer[1] = num4;
        }
        num = BitConverter.ToInt16(buffer, 0);
    }
    catch (Exception exception)
    {
        throw exception;
    }
    return num;
}

Dave
BTW, in software, hope and pray is not a viable strategy. (Luc Pattyn)
Visual Basic is not used by normal people so we're not covering it here. (Uncyclopedia)

J4amieC4-Nov-08 5:26

4-Nov-08 5:26

Yeah, I saw that but I was attempting to avoid the use of nasty VB namespaces Dead | X|

DaveyM694-Nov-08 5:32

DaveyM69

4-Nov-08 5:32

J4amieC wrote:
nasty VB

If you use the code above you don't need to - it's just that function converted to C#

Dave
BTW, in software, hope and pray is not a viable strategy. (Luc Pattyn)
Visual Basic is not used by normal people so we're not covering it here. (Uncyclopedia)

PIEBALDconsult4-Nov-08 4:34

PIEBALDconsult

4-Nov-08 4:34

J4amieC wrote:
As you can see, simple code & easy to port but very different results

No, I can't see; what are the results?

Provided you don't care about Unicode, you could use:

System.Text.Encoding.ASCII.GetBytes()

and

System.Text.Encoding.ASCII.GetString()

You could also access the characters in an unsafe context much like your VB code. Something like:

private unsafe static void
ASCIIize
(
    string Subject
)
{
    fixed ( char* subject = Subject )
    {
        int* length = (int*) subject - 1 ;
        int  index  = 0 ;
 
        while ( index < *length )
        {
            *(subject + index) &= (char) 0x7F ;
 
            index++ ;
        }
    }
 
    return ;
}

(Though I haven't tested this with the problematic characters.)

J4amieC4-Nov-08 5:28

How to create my own button [usercontrol? or what?]

4-Nov-08 5:28

PIEBALDconsult wrote:
No, I can't see; what are the results?

The results are cryptic, horrible and mostly non-printable characters which is why I didnt post them. I meant the code was easy enough to port on the face of it.

Matjaz-xyz4-Nov-08 2:34

Matjaz-xyz

4-Nov-08 2:34

Hi.

I have a question on how to create myself a completly new button and use it anywhere i want in my project.

I want to have a button with three pictures. One on click (green as currently selected) one on unavaliable ( red ) and one on avaliable (blue).

For better understanding - i have a miniproject on creating an example of cinema tickets sale. A user selectes in a cinema hall (dont know how its called) a few displayed seats, which are marked blue (as avaliable). and when the operator clicks on it - it turns green and if these tickets are bought the buttons goes red and is unavaliable for further clicking...

i hope its ok explained.

so, i was saying... i could create a few buttons on hand - drag a picturebox. on click - the picture would change its picture to green one and if it was bought - another red picture would be writen. So i want to create a usercontrol with these things.

Is it even possible? or do u have any other solutions for me?

example : Link to a picture[^]

and the number of seats would be generated by user ( 3x4 or 5x1 or etc...)

Força Barça!

modified on Tuesday, November 4, 2008 8:47 AM

Re: How to create my own button [usercontrol? or what?]

cyber-drugs4-Nov-08 3:34

cyber-drugs

4-Nov-08 3:34

Personally, I would use GDI to draw the seats on the form, and just color/colour them accordingly from the availability and events as you mentioned above.

However, if you prefer to use buttons, you can. You need not create a new button, you can merely change the background color/colour of each button to which ever you require, and then create an event that iterates through each button on the page, stating that if they are clicked and their color/colour is X, set it to Y.

If you insist on a user control, you merely need to create a simple 25x25 pixel user control (or whatever size you want each seat), create an enum value for each state (reserved, un-reserved, etc), and then create a public property to set the "state" of that seat. When the value is changed, you also change the background color/colour of the user control to which ever you require.

There are many methods to achieve what you are after. Smile | :)

Re: How to create my own button [usercontrol? or what?]

Matjaz-xyz4-Nov-08 3:41

Matjaz-xyz

4-Nov-08 3:41

Great. Thanks Smile | :)

But i have another question and i dont want to open a new topic :
How to create a specific number of objects X x Y?

6 buttons in a row in 3 columns (6x3)?

And how to add a diferent action on click for different button?

Im sorry for so many questions, as i dont have so much knowladge in C# and i just started to learn properly and whats the best way to learn than through examples Smile | :)

Thanks again,
Matjaž

Força Barça!

Re: How to create my own button [usercontrol? or what?]

cyber-drugs4-Nov-08 3:54

cyber-drugs

4-Nov-08 3:54

Unfortunately I'm in a training course at the moment, so I have limited resources to my disposal. If nobody else replies by the time I get home this evening, I will send you some sample code.

[EDIT]

DaveyM69 seems to have beaten me to it. Smile | :)

Re: How to create my own button [usercontrol? or what?] [modified]

DaveyM694-Nov-08 3:47

DaveyM69

4-Nov-08 3:47

you don't really need a button - just derive from Control and have an Availability property, override OnClick to set the availability and OnPaint to do the painting.

A very rough mockup to get you started:

using System;
using System.Drawing;
using System.Windows.Forms;

namespace MyControls
{
    public enum Availability
    {
        Available,
        Unavailable,
        Selected,
    }
    public class TriColorButton : Control
    {
        public event EventHandler AvailabilityChanged;
        private Availability availability;
        public Availability Availability
        {
            get { return availability; }
            set
            {
                if (availability != value)
                {
                    availability = value;
                    OnAvailabilityChanged(EventArgs.Empty);
                }
            }
        }
        protected virtual void OnAvailabilityChanged(EventArgs e)
        {
            Invalidate();
            EventHandler handler = AvailabilityChanged;
            if (handler != null)
                AvailabilityChanged(this, e);
        }
        protected override void OnClick(EventArgs e)
        {
            if (availability == Availability.Available)
                Availability = Availability.Selected;
            else if (availability == Availability.Selected)
                Availability = Availability.Available;
            base.OnClick(e);
        }
        protected override void OnPaint(PaintEventArgs e)
        {
            switch (availability)
            {
                case Availability.Unavailable:
                    e.Graphics.FillRectangle(Brushes.Red, e.ClipRectangle);
                    break;
                case Availability.Selected:
                    e.Graphics.FillRectangle(Brushes.Green, e.ClipRectangle);
                    break;
                default:
                    e.Graphics.FillRectangle(Brushes.Blue, e.ClipRectangle);
                    break;
            }
            base.OnPaint(e);
        }
    }
}

[edit]forgot the event keyword! Blush | :O

[/edit]

Dave
BTW, in software, hope and pray is not a viable strategy. (Luc Pattyn)
Visual Basic is not used by normal people so we're not covering it here. (Uncyclopedia)

modified on Tuesday, November 4, 2008 9:59 AM

How do display a form in a seperate thread

EliottA4-Nov-08 2:27

EliottA

4-Nov-08 2:27

I tried browsing for a simplistic threading tutorial / article with no avail, a lot went into to much detail t ha is a little to complex for me right now. All I want to do is launch a form in a seperate thread as my main form is laggy because of a bunch of loops that goes on in it.

Any ideas or suggestions as to what to read to get a basic grip of threading?

dybs4-Nov-08 2:41

dybs

4-Nov-08 2:41

Are the loops used for creating or updating form controls, or just doing other data processing? If not for form controls, then could you put all that work in a separate thread? It might make your main form less "laggy".

Another idea might be to call

Application.DoEvents()

at the end of each loop iteration. I've seen some people prefer to avoid this method, but I've personally used it without much trouble. This should keep your form responsive.

Brandon

Dave Kreskowiak4-Nov-08 3:35

Dave Kreskowiak

4-Nov-08 3:35

EliottA wrote:
All I want to do is launch a form in a seperate thread

You cannot do this. All GUI, including other forms, must be launched on the app's main (GUI) thread. If you try to do this on another thread, it may work one time, but not another, and you'll get strange behaviors in the forms controls and rendering issues.

You put your work on other threads and Invoke functions on the forms to modify the controls for your threaded code. You cannot directly modify controls on threads other than the one that created the control.

A guide to posting questions on CodeProject[^]

Dave Kreskowiak
Microsoft MVP
Visual Developer - Visual Basic
2006, 2007, 2008

EliottA4-Nov-08 5:21

EliottA

4-Nov-08 5:21

So you're saying instead of attempting to load a form through a new thread, i should put my infinite loop which reprocesses data continuously in a seperate thread? (Take my loop out of the GUI thread?)