Class Property Arrays Not Holding/ Updating Values
Oct 1, 2011
I am trying to use several Class arrays to hold values that I will cycle through at a later point to perform some calculations. I need to change the array sizes to fit the data as it is entered. I am using one procedure to set the first element of each array and then a separate procedure to pass the additional values as they are entered.
Until my last attempt at changing my code, my StartBalance sub seemed to work, I could step through and see the values assigned to the class arrays in the code block. However, when it moved on to the Transaction sub, it did not recognize that the first set of values were set, the array shows zero values for index 1.
I have gone through several changes trying different ideas from reading blogs and articles, but I guess I am not understanding how these work. I even used the class arrays directly instead of the Property procedures to see if I would get a different result, but I do not.
I believe I must be approaching this incorrectly and though I can find dozens of examples of setting class variables and even a couple on using arrays as class variable, I can not find any that show how to then pass values to those arrays.
Public Class Statement
Private _tranDate(1) As Date
Private _amount(1) As Double
[Code]....
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Jun 2, 2012
I have created a new class with a string property called "Text".
The property will hold a sentence typed by the user.
I use "KeyPress" event to get the character pressed and use "Console.Text = Console.Text & e.KeyChar" to update the property. Where console is an instance of the class.
The problem is when I press "Delete" nothing happen.
That's the code within the event scope
MsgBox(Asc(e.KeyChar))
Console.Text = Console.Text & e.KeyChar
MsgBox(Console.Text)
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Jul 5, 2010
bare with me during this silly example. :-) Let's say I have a class like this:
Public Class Animal
Public iLegs as int32 ' Number of legs
Public bWings as Boolean ' Wings? Yes/No
End Class
And another class that inherits the "Animal" class and adds one more property:
Public Class ScaryAnimal
Inherits Animal
Public iScariness as int32 ' 0-100, how scary is it?
End Class
Now, if I have an instance of "Animal" with some values in it, and I decide I want to cast it to a ScaryAnimal for some reason, how do I do that without having to create a new instance of "ScaryAnimal" and copy each property value?Basically I'm looking for a way to do this, without having to write the lines marked with '*** below:
[Code]...
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Jun 21, 2010
I have valued pairs, attributes names and values in one hand, and I have an object with attributes. I need to set the values of those attributes. I need something like [code]
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Oct 1, 2009
I am creating an ASP.Net page with VB.Net codebehind. I am using a class variable to hold data (named ods see below) from a SQL Server query so I do not have to keep going back out to the server. The class variable gets loaded ok and I populate a grid data with this dataset. However when I need to go back in and reference the dataset again, I get an error and I come to find out my dataset no longer holds the data.
Here is my declaration in my code behind:
Partial Public
Class LotTrackingMain
Inherits System.Web.UI.Page
Private con
As SqlConnection =
Nothing
Private ods
As
New DataSet
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Aug 26, 2011
I would like to update string arrays in batchlets say I have 3 string arraysI want to for example redim them and then up load them with data.I have tried for each on array of arrayI have tried list.at the end none of them are updated.
Dim Str1(10) As String
Dim Str2(10) As String
Dim Str3(10) As String
[code].....
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Aug 25, 2009
Using MSDN documentation on creating Control Arrays in VB.net I proceeded to create a control array based on my UserControl. I modified the code programmatically to Loop through a For-Next loop to create 6 objects using the same UserControl. After creating these objects, I proceed to perform graphics on each control to draw a rectangle of which is in the center of the control by using a Timer_Tick event.
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Nov 15, 2011
Below you will find a code sample that I have dummied up to try and demonstrate the issue I am having. However, this is just a dummied up piece of code. The actual program has noting to do with STUDENTS or TEACHERS. Basically, the problem I'm having is trying to have a CLASS within another CLASS each of which contain ARRAYS that need to be dynamic in size. The sample has a CLASS called STUDENTS that can have in theory many students, the number of which are unknown to the CLASS. I need to be able to add STUDENTS to the ARRAY programmatically.
The CLASSROOM Class should also be an Array since each TEACHER will have MANY Students. There will be only 1 Teacher for a given classroom but the SCHOOL will have MANY CLASSROOMS. Again, I need to programmatically add Teachers and Students without having predefined Array sizes. The code I have listed below will NOT work but it demonstrates what I am trying to achieve. I want to be able to reference the CLASS by using something like this ...
School(iTeacherIndex).Student(iStudentIndex) = "Rick Smith"
I feel like I should be able to use ARRAYLIST in both classes but haven't been able to get it to work. I've tried DIM'ing as ARRAY and can't get that to work either.If I can get ARRAYLIST to work then I shouldn't need to worry about expanding the array via UBOUND (if it's even possible).The REAL question is "How do I have a CLASS within a CLASS, each of which has ARRAYS that need to be dynamic in nature so they can be expanded as needed? The size of the array cannot be determined ahead of time".
REMEMBER . . . the actual program has nothing to do with Students and Teachers. This was just my way of demonstrating the issue using an analogy that I thought everyone could understand. The actual Class is much more involved.I have purposely hardcoded some values just to make the sample easier to work with. This is NOT how I normally program but is just here to hopefully make things a little more clear.
Here is the sample code . . .
'***********************************************************************************
'***********************************************************************************
'***********************************************************************************
'Here is the code that is in the form - This obviously doesn't work
Private Sub TeacherTestDemo()
Dim iTeacherIndex As Byte
Dim iStudentIndex As Byte
[code]....
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Jan 12, 2011
Ok, I want to create a class that will handle a special rectangle graphic.In my form, I want to have two of these special rectangles. So, basically, I need two instances of that class in my form, right?I manage to initialize two, alright. But, how exactly am I supposed tomanage drawing/graphics etc in a class, and the results to be displayed in my form?
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Jun 1, 2012
I have a very simple class that holds a few public properties - ID, Text, Colour, etc. and a Boolean called 'SelectedItem'. Just like the Checked property on RadioButtons, only one item can have its SelectedItem property set to True within a particular group. Note: there will be several separate groups (lists), each allowed to have only one item with SelectedItem = True.
My first thought was that I would probably just have to handle everything outside of the class, setting SelectedItem to False for every other item in a particular list when another item was selected. But that seems rather inelegant to me. So I've been trying to think of how this might be done within the class. For example: could I perhaps have a private string property called say "GroupName" - set in the New sub when adding a new instance of the class - and then use a private shared method to set every item's SelectedItem property to False, provided the item has the same GroupName as the newly selected item? I would have a go at doing this but I have no idea how to enumerate every instance of a class from within that class, or whether that's even possible. Is it? Or is there another (better) way to achieve my goal? Here is a cut-down version of what I've got so far:
Public Class ResourceItem
Public ID As Integer
Public Text As String[code]....
As can be seen: instead of instantiating a new ResourceItem and passing that as an argument to the manager's Add procedure, I'm simply passing the details of the new item and the procedure is creating the item from those. I don't know whether this is a good or bad idea - please advise - but I've done it because I couldn't figure out how to make the SelectedItem property only writeable by the manager, so I wanted to avoid having directly accessible objects that could have their SelectedItem property set to True without it deselecting all the other items in the same group. Of course that still leaves the possibility of setting a variable to one of the manager's list items and setting it from there, so I would still like to know how I could prevent that, if possible.
UPDATE: I didn't use the code above in the end, deciding instead to go with Cyborgx37's solution - which seems to work perfectly well for me despite the warnings about best practice. I also realised I would need to use the same class in another scenario where multiple items could be selected, so it was easy to add a Boolean property to the manager to enable that.
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Aug 13, 2009
I have the following code:
Public Class MyColorsClass
'Constructors
Public Sub New()
'Empty Constructor
[code]....
However, if the empty constructor was called to instatiate this class then the colortype is not yet set. Therefore, if one accesses the 'IsColorCool' property it will always return 'False'. Now for the sake of this example, I must keep the empty constructor as part of the class.Now I could add some code in the 'IsPropertyCool' to check and see if a ColorType has been defined, and throw an exception if it has not been set, but I don't really want to do that.I also could always move the logic OUT of the property and into a method on the class called 'DefineIfColorIsCool' or something, and make the owness on the caller to make sure the method was called if they want to use the property 'IsColorCool'?
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Feb 17, 2011
It seems as if the propertygrid control cannot display property arrays. Is this the case?
When I do this :
Imports System.ComponentModel
Public Class comPicturePirate
Private intAmountImages As Integer
Private strWebURL As String
[Code]...
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Apr 7, 2011
Supose a base class
Public Class airplane
Private var_num_seats As Integer
Private var_num_engines As Integer
[code]....
Obviously, I don't wish that the class Glider has the method "start_engines" neither the property "num_engines". Otherwise, other child classes may have. How can I supress these property and method in child class, not just ignoring (if I can)?
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Sep 29, 2011
I have procedure (Import) that calls a for a new instance of frmImportData. I also have a class name clsBatch that has a data table property called prpParametersTable.For some reason, I get an error (indicated below with ERROR>>>) when trying to assign prpParameterTable to cv_dtImport2. The error states "Object reference not set to an instance of an object.". Why does this error not happen when I assign dtBP to cv_dtImport1? Both cv_dtImport1 and cv_dtImport2 are equal to Nothing and in my Import procedure dtBP = prpParametersTable.
Public Sub Import(ByVal clsB As clsBatch)
Try
Me.cv_clsB = clsB
[code]....
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Nov 14, 2009
I have three class files, accounts.vb and transactions.vb in addition to my form.vb. I am unable to retrieve a member variable from on class from inside the other. When the combobox index changes, the program loads the correct account (checking or saving) from two different sequential files. I don't think I have the calcBalance procedure in the correct class file. And that is what I am having trouble with. Accessing it to display it. [Code]
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Mar 30, 2010
This is a bit of a continuation from a previous post for which AtmaWeapon was very informative.
Problem:
A parent class has a sub class with various properties. A property of the parent class is a List(of T) with T = the sub class The issue is how to store data in the sub class of the instantiated parent
Some example code (hopefully formatted correctly):
Code:
'=========== Class Definitions =============
Public Class courseClass
Public Class timeTableClass
[Code].....
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Apr 2, 2010
I'm looking for a tutorial on how to Adding a list(of Class) or Collection as another Class's Property.What I am after is something like the Columns Collection for the DatagridView control.I would like to add Items in the graphics screen. Where the item list is displayed in the left panel and the selected Item properties are displayed in the right panel.
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Apr 26, 2012
I'm making an application in school where I have to display the values of domestic, international, and total sales of company "Conway Enterprises." Everything seems to be working except it is not displaying the totalCompany sales as a currency. I'm sure it's probably an easy fix but I've been searching the internet and re-reading my book for awhile with no results. Below is the code, as I said everything seems to be working fine aside from adding the two array values and then displaying them as currency.
Public Class Form1
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
End Sub
[code]....
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Sep 28, 2011
I have a program in VB.net that uses a 3D array:
Private gridList(10, 900, 900) As GridElement
Now, I just used a Memory Profiler on it (because my application is having some major leak issues or something) and apparently, this array (containing at the moment of testing 0-30 elements at one time) is using 94% of the memory currently in use by my application. Even when it is empty it takes up huge amounts of memory.
My only assumption is that even empty arrays take up space! This puts a major blow into my plans!
My Question:
Is there any alternative to this that allows me to still have the same abilities to map i.g. I've been using it like this:
Dim cGE as GridElement = gridList(3, 5, 7)
but doesn't hog up so much memory for things that aren't using memory?
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Sep 27, 2011
I'm using a structure to hold three arrays:
structure myStruct
dim arrayOne() as char
dim arrayTwo() as char
dim arrayThree() as char
end structure
But how do I go about setting them a value, I've got my instance of myStruct
dim aStruct as new myStruct()
If I try redim, it just tells me it can't change the dimensions of an array, so how do I got about initializing the arrays with values?
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Oct 22, 2009
I have two arrays with equals number of values, is there a way to match the values exactly in same order, as such:
FirstArray("1,"2","3","4")
SecondArray("John","Samantha","Tony","Joe")
1---John
[Code].....
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Sep 25, 2010
I am working on a program where I need to multiply the value (int) times the value (dec) of another array to calculate the total cost of books in inventory. [code]....
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Mar 4, 2010
i am working on a VB project for Chem and im making it for converting grams to moles, moles to molecules or any thing like that. and i have about 110 elements set up and working fine the way that im doing it but i have a feeling this is a horrible way and to abundant.
i have a textbox set up to if i type in the element He and hit enter it will find ChemElement(1)="He" and it calls "Sub DisplayElement(ByVal number As Decimal, ByRef label2 As Label)"
Which then displays the Chemical mass into a Label.
[Code]...
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Apr 30, 2009
What should the set/get function look like for the following class?[code]...
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May 22, 2010
This section of code is part of a much larger program.However, I can't seem to find the problem with this error.Error: Object reference not set to an instance of an object.[code]I'm using this array inside of a class form to maintain the memory of a computer player in a rock, paper, scissors game. There are two computer players involved; thus, the need for a unique instance of each array for each player.I'm struggling with this program and all of my errors are gone until I try to run the main form.I can link more code if needed.
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Apr 19, 2010
I have a windows form which contains a textbox.I have a loop in my code doing some farly intensive work. In the middle of the loop I want to update my text box.text property on the form to let my users see some simple progress.
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Feb 28, 2010
How can to make control arrays in vb.net ? there is no INDEX property or Load method like VB6. so how i can do it ?
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Jun 3, 2011
im a newbie here, im taking intro to programming wth VB in college and im having problem with the homework here's what im supposed to do
[Code]...
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Apr 23, 2009
All variables and Arrays have been declared properly the problem Is when the user enters a new number using a scroll bar
LottoNumber = HScrollBar1.Value
Label2.Text = "Number Selected: " & LottoNumber
The out put of the variable count stays at 1 so the output stays at (Pick # 1 of 6) and doesnt increment at all and does not build the OutPut string
'IF The LottoNumber Location Value is 0 in the Array selectedLotto THEN mark it by making the Loacation Value to 1
If selectedLotto(LottoNumber) = 0 Then
[Code]....
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Feb 18, 2010
Why can't I declare values for an array inside a module?
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