Visual Basic

newbie question: arraylist and dictionary

3-Jun-04 2:34

You haven't submitted any code, so we really can't tell you what your doing wrong. But, if I understand you correctly, how you are trying to do this might look something like this:?

Public Class A
    Dim objB As New ClassB
End Class

Public Class B
    Dim objA As New ClassA
End Class

IIRC, this is not going to compile because of the circular reference you are talking about. It's just bad object designed to have two classes completely dependent on each other. You're classes should be designed so that they are self contained modules and have a one way relationship:

Public ClassA
    Dim objB As New ClassB
End Class

Public ClassB
    ' no code dependent on class A existing here...
End Class

RageInTheMachine9532
"...a pungent, ghastly, stinky piece of cheese!" -- The Roaming Gnome

fuel2run1-Jun-04 21:48

fuel2run

1-Jun-04 21:48

hi there,

when is suitable using a dictionary instead of an arraylist and wayback?

i mean, i can't retrieve an object from an arraylist using a string key, is it?

there are other difference/condition? i.e. array dimension or whatever?

thanks in advance!
fuel2run

Re: newbie question: arraylist and dictionary

Dave Kreskowiak2-Jun-04 12:21

Re: newbie question: arraylist and dictionary

2-Jun-04 12:21

If you want to use a String type key to retrieve data then you have to use a class that implements IDictionary, like a HashTable or SortedList. There are other classes, but those seem like they'll fit your needs. Anything that implements IDictionary is accessed by a key/value pair. You give it the key as a kind of index and the IDictionary will return the value associated with it.

ArrayList's are accessed by an Index value, usually an Integer type.

RageInTheMachine9532
"...a pungent, ghastly, stinky piece of cheese!" -- The Roaming Gnome

fuel2run2-Jun-04 20:59

fuel2run

2-Jun-04 20:59

thank you!
F2R

How can I send a message to another computer?

tramdtt1-Jun-04 20:42

tramdtt

1-Jun-04 20:42

I want to send a message to another computer by writing VB!!! Who can help me???
Thanks

tramdtt

Colin Angus Mackay1-Jun-04 22:32

Colin Angus Mackay

1-Jun-04 22:32

There are a number of ways to send "messages" to other computers. Could you be more explicit in your request. Is the message aimed at a user, an existing process/application, another application you are writing, etc.?

"You can have everything in life you want if you will just help enough other people get what they want." --Zig Ziglar

The Second EuroCPian Event will be in Brussels on the 4th of September

Can't manage to P/Invoke that Win32 API in .NET? Why not do interop the wiki way!

tramdtt1-Jun-04 23:27

tramdtt

1-Jun-04 23:27

Hi, Colin Angus Mackay
Thank for your answer. But can u say more clearly? I am writing a program which send and receive files using Winsock. But i want to send a message to received computer to notice whenever a file is sent to.
Which functions can I use to send message to received computer? I write in VB6,0.
Help me
Thank

tramdtt

^eleK2-Jun-04 9:13

^eleK

2-Jun-04 9:13

Just use a socket and sent it a simple string saying it's done. There's exhaustive information about writing sockets on the net and in the MSDN.

Dave Kreskowiak2-Jun-04 12:15

2-Jun-04 12:15

When you send the message, is there going to be a client app on the detination computer that will recieve this message? If not, you'll need one!

RageInTheMachine9532
"...a pungent, ghastly, stinky piece of cheese!" -- The Roaming Gnome

tramdtt2-Jun-04 14:58

tramdtt

2-Jun-04 14:58

I use Winsock to write a app send and receive files throughout computers on LAN. I used to use SendData method to send a string to app of destination computer . But I want to send a message to notice to destination computer whenever files are delivered to destination computer.
Which functions Can I use in this situation?
Help me!
Thanks

tramdtt

API / Hooking challenge

ColonelSanders1-Jun-04 18:08

ColonelSanders

1-Jun-04 18:08

I have a global system hook, using "dscwpmsg.dll" and an example from www.allapi.net (acording to the read me: a system wide Hook of the types "WH_CALLWNDPROC" and/or "WH_GETMESSAGE").

I want to know when the a user RIGHT clicks on the minimize (or any other) button of the control box (top right of every window).

If any one has any ideas I'd appriciate it. And before any one sais you can't (people on IRC caim it is not possible): it is possible, I have an application that does it, now I want to know how...

vb.net class

pnpfriend1-Jun-04 16:50

pnpfriend

1-Jun-04 16:50

Hello..I'm new in VB.net
I have form with display button and text box.
I have myclass.

<br />
Namespace theClass<br />
<br />
<br />
    ' The class is named StringProcessor.<br />
    Public Class myClass<br />
<br />
 Public Sub printOut(ByVal t as String)<br />
<br />
MsgBox(t)<br />
End Sub<br />
End Class<br />
End Namespace<br />

Then I want to print out what the use type in so I call
printOut(Me.InputText.Text)

but I got error message like
An unhandled exception of type 'System.NullReferenceException' occurred in BrianHuang_Unit5.exe

Additional information: Object reference not set to an instance of an object.

help me how to correct it please.

Colin Angus Mackay1-Jun-04 22:37

Colin Angus Mackay

1-Jun-04 22:37

You don't give the stack trace of the error message, so it is harder to tell WHERE it happened.

Given the code snippet you've supplied Me.InputText is the most likely culprit, if so that means you have not set it to an instance of an object. You need to instantiate Me.InputText first.

Dave Kreskowiak2-Jun-04 0:32

2-Jun-04 0:32

We need to know on what line the exception occured, otherwise we really can't tell you with any accuracy what you did wrong.

RageInTheMachine9532
"...a pungent, ghastly, stinky piece of cheese!" -- The Roaming Gnome

pnpfriend2-Jun-04 6:02

pnpfriend

2-Jun-04 6:02

This is in form.

<br />
 Private Sub btnDisplay_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnDisplay.Click<br />
        Dim sp As Course.theClass.myApp<br />
        sp.printOut(Me.InputText.Text())  ' here the error pointing to.<br />
    End Sub<br />

the myApp class

<br />
Option Strict On<br />
Option Explicit On <br />
<br />
Imports System.Windows.Forms<br />
<br />
' The class module is enclose in a namespace named CountingStatement. <br />
' The root namespace was set to Course using the Project Properties dialog box. <br />
Namespace theClass<br />
<br />
    ' The class is named StringProcessor.<br />
    Public Class myApp<br />
        Public Sub printOut(ByVal theText As String)<br />
            'get the total number of characters,#of Words, #of paragraph, and # of sentence in that paragraph. <br />
            MsgBox (theText)<br />
        End Sub<br />
    End Class<br />
End Namespace<br />

It is not as easy as c++. I dont know how to call the class function from the other class in VB.net.

Thank you

Dave Kreskowiak2-Jun-04 12:14

2-Jun-04 12:14

The problem is that you delcared sp as Course.theClass.myApp, but you never instantiated it. It should be:

Dim sp As New Course.theClass.MyApp

RageInTheMachine9532
"...a pungent, ghastly, stinky piece of cheese!" -- The Roaming Gnome

user validation in vb.net

Anonymous3-Jun-04 10:50

Anonymous

3-Jun-04 10:50

thank you... it works now.

vince campellone1-Jun-04 13:52

vince campellone

1-Jun-04 13:52

does anyone know somewhere when they have written code to verify what users are signed onto a program.

for example. If i only want 10 users logged in at once but 100 possible users in the program. Each instance will be running on a diff pc and i cant figure out how to validate what users are logged on and limit the logged on users to 10

Vince

Re: user validation in vb.net

Dave Kreskowiak1-Jun-04 15:08