Declaring A New Class Within A Sub?
Feb 22, 2011
Ok, basically i have 3 different classes: one is a NormalUser, one is a SuperUser, and one is an Administrator. I have on one of my form loads an if statement like this:
If frmLogin.lstCurrentUserData(frmLogin.lstCurrentUserData.Count - 1).Contains("Normal") Then
Dim player As New NormalUser
[Code]....
So based on an item in a list, i want to create a new instance of that class to be my player. now i know that code doesn't work, because the variable is only present within the if statement. my question is, how can i declare "player" as a new instance of the correct type, and still be able to access it in other subs?
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Nov 23, 2009
I had a problem with CLR profiler. But it worked eventually and the results were outstanding. My app took 47 milliseconds to run before and after some adjustments CLR profiler runs in 6 miliseconds! This had to do with String values in a resource file which apparently takes a lot of time. So this got me thinking, isn't it more effective if you would declare 1 String at the top of your class and constantly change it throughout your code? Instead of creating a new String in a method when you need it.
Instead of using:
Dim text = "blalblalba"
You would do this everytime you needed a string:
text = "blalbla"
My question is... What exactly happens when you say text = ""? Does .net create a new String? It looks like you replace the text but what happens in the background? Would it be faster then declaring a new string?
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Mar 5, 2010
What's the proper way to declare variables in a class? I've been doing something like:
'in a class
public shared teststring As String = "first"
'on a code behind
[Code]....
with shared variables loading a second window or reloading the page (without clicking the button) renders the hello world string. so how do I declare variables in a class but make it per instance?
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Mar 30, 2011
I'm trying to develop a class in VB .NET in order to manage a language globalization stored in a database and editable by the user.What I need is to know what kind of class I need to declare in order to use it without declaring a new object. For example, the way My.Settings is used.
One of the goals is that in some project the developer imports the reference and after that access directly to a property. For example: My.CustomLanguage.GetWord("Hello") without declaring objects.
Is this possible? And if it's what is the best way to aproach it?
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Apr 5, 2011
I have a class that I would like to link at construction to a given control (say a textbox)
I know I can put a variable into a subroutine referentially but is there a way to store it in the same capacity?
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Oct 20, 2008
I've decided to forget the d@mned custom code because everything I do with comes up with errors I don't know how to fix and it seems no one else does either. Or they do and they're keeping to themselves.
I put the functions that I needed to use in a class called MsgBoxOperations. The file name is MsgBoxOperations.vb In the report, up on the standard bar where file, edit, view, and all the other stuff is, is one that says report. You click that and go to report properties and it brings up where you can name the report and put in custom code...(hate custom code right now...) and where you can put references and class instances. Clicking on the Reference tab brings up wher you put in your references and classes.
In the classes area it asks for the Class Name, which I put in MsgBoxOperations, and the instance name of that class, this case mbo. I get that far and put in those two things and save it. Then I go to the textboxes where the values need to be. I put in the text box: =Code.mbo.GetStartDate
I've already tried taking the Code. part out and it screams that mbo isn't declared. So it does have to be there. I go to run the code and comes up with this error: QuoteError in class instance declaration for class MsgBoxOperations: [BC30002] Type 'MsgBoxOperations' is not defined.
I've posted before and still have received no help or someone tried to help but then stopped when their suggestion failed and then no one else wanted to help. I've googled this problem to the point where every link that it comes up with I have already clicked and found their information useless. I've got a freaking migraine because of this issue and have been in tears over it more than once.
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Jun 28, 2009
how do i use a class without first declaring an instance of it with the new keyword?i have a class items that has a function toArray.how can i call it this way:
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Aug 5, 2010
I have a base class foo that will be used in multiple child classes of similar but slightly different function:
Public MustInherit Class foo
Public Function bar1() as Something
''// Perfectly OK to change what this method does
[code]....
How do I get the compiler to generate an error when bar2() is overridden by a child class?
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Jan 6, 2011
Is it possible for a class of exposing a type for function returns, without allowing users of that class to create variables of that type? A couple usage scenarios:A Fluent interface on a large class; a statement like "foo=bar.WithX(5).WithY(9).WithZ(19);" would be inefficient if it had to create three new instances of the class, but could be much more efficient if the WithX could create one instance, and the other statements could simply use it.A class may wish to support a statement like "foo[19].x = 9;" even when foo itself isn't an array, and does not hold the data in class instances that can be exposed to the public; one way to do that is to have foo[19] return a struct which holds a reference to 'foo' and the value '19', and has a member property 'x' which could call "foo.SetXValue(19, 9);" Such a struct could have a conversion operator to convert itself to the "apparent" type of foo[19].In both of these scenarios, storing the value returned by a method or property into a variable and then using it more than once would cause strange behavior. It would be desirable if the designer of the class exposing such methods or properties could ensure that callers wouldn't be able to use them more than once. Is there any practical way to accomplish that?In formulating a question, it's difficult sometimes to draw the line between complicated usage cases, and simpler usage cases which aren't quite so important. Here's another usage case, and one closer to the one I'd be most interested in (though I'm also interested in Fluent chaining; being able to have something behave like a C++ reference to a value type would be nice, but probably too much work to bother with).I have a type which is somewhat like the Windows registry, in that it is a hierarchical collection of items, each of which may have a string value, an integer value, and/or a nested collection of items. I wish to be able to support the following types of usage:[code]As for the Fluent interface, my thought would be to have the WithXXX properties return a new instance of a derived class which shadows (not overrides!) the WithXXX properties with versions that simply modify the current instance. The return object from WithXXX would be known to be of the derived class, and would thus use the shadowed WithXXX methods, but once it was assigned to a variable, it would be regarded as an instance of the base class, so the next WithXXX would create a new instance.
C++ a stronger concept of value types than C# or vb.net, including the very useful concept of references to value types; it ensures that references to value types cannot be persisted outside the scope of the type in question. Unsafe code in C# can use pointers to value types, but they don't have the protections offered by C++ references.
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Sep 26, 2011
I have a collection of objects (classes I created), and each one ties to a record in a database. I want an easy way to update the information, so I thought about declaring a record in the class, that would tie to the record on the database. However, I'm having a problem updating it now.
1) Can I declare a global variable for the data context, and leave it open the entire time the program is running? This would solve my problem, but I don't know if I can do that.
2) If not, besides coming up with a complicated class to do this, is there an easier way? Here is an example of what I am trying to do:
VB.NET
Public C as Record
Public Sub GetValue()
Dim SQL As New DBDataContext
Dim X = From T in SQL.Records Select T
[Code] .....
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Jun 27, 2011
I'm writing a class that represents a diagram (an image). Within that class, there is textbox class. That is, each diagram can have any number of textboxes on it. I want each instance of the textbox class to have access to the members of its parent diagram class. Specifically, I would like each textbox class to be able to access the instance of the Drawing.Graphics object located in the parent Diagram, so it can handle the drawing of itself
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Mar 12, 2010
What is the difference between using the 'array' class in VB and just declaring an array like normal. In other words, what is the difference between:
Dim numOfTicketsPerDay As Array
Dim intNumOfTicketsPerDay(6)
As Integer
Is there any preference of when one should be used over another?
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Oct 5, 2009
If you want a instance of an object to be created when a form loads or another class is created, you have two options:
Public class example
private IAmAObject As IAmAObject
public sub new()
[CODE]...
Or like this:
public class example
private IAmAObject as new IAmAObject
public sub new()
[CODE]...
I always use the first one. It's more type work but I think it's neater. How about you people and is there any real difference between the two?
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Apr 20, 2012
How can I convert the following code into VB.Net?
private const UInt32 temp = 0xE6359A60;
I tried the following but it doesn't work.
Public Const temp As System.UInt32 = 0xE6359A60
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Apr 13, 2010
We have a great book written for Visual Basic 2005 that we type code that is prepared in advance. We are using Visual Basic Express 2008 and normally this works really great; type the code run the program and it works, however I am running into a snag.
The textbook shows the following code: IN THE(General) (Declarations)AREA we are told to type the following:
' Create a Graphic object to use with the game's bitmap
Dim myGraphicObject As Graphics = Me.CreateGraphics
' Create an empty Bitmap Object
[Code].....
is there a difference between VB 2005 and VB 2008 that would be causing the errors? or am I missing something subtle maybe mistyped?
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Jun 18, 2010
In the middle of attaching a Google Custom Search Engine onto my page,I have a string which I would declare in C# as
String rxPattern = "<(?>"[^"]"|'[^']'|[^'">])*>";
How do I convert it to a string in VB?I mean store the same value into the string variable rxPattern using VB/VB.NET?
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Apr 7, 2010
I have 12 checkboxes jan, feb, ..... dec i want to display the checked checkboxes into a file i know how to write in the file but the format of displaying checkboxes is as follows if i checked jan, feb,march and april then output is jan,feb,march,april here my problem is how to collect checked value in array , and how to put comma betweem them.
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Jan 8, 2009
How would you declare constants from a .dll, so you can use it in your program.
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Apr 26, 2011
Trying to declare some arrays. I haven't worked with them that I remember. I always took the long road, of declaring each and every variable, but would like to learn this method. The problem is I'm having trouble with the methods I'm finding on the net..[code]for some reason there is a squiggly under each MonsterName except in the declaration that says "declaration expected"
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Apr 12, 2011
visual basic 2008 express
' the following lines declare the variables and constants
Dim intDiameter As Integer
Const dblPI As Double = 3.14159
Const dblAREA As Double = 140125
Dim intLabel As Integer
Private Sub PizaSliceCalculator_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
[Code]...
I made a working program to calculate piza slices, i was told i needed to declare pi and the areas as constants. when i rewrote the program it no longer works. the result keeps coming back as 0.
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Sep 2, 2009
I haven't check yet all the new features of ASP.NET 4.0 but I'm wondering if one of those features (VB syntax) is declaration of class properties oppose to C# in less code.[code]
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Mar 2, 2012
I've got a problem in the display of controls on a form. The form controls are fine on my development system, but when installed on another machine, (same operating system, but evidently some other installed objects), the textbox controls in some of the forms have a black backcolor. Some of the tabs are pure white with the blacked out textboxes, some are the normal color. Some of the textboxes in the other sections are fine, some are not.
Is there any way that I can declare that all my controls are to be the 'standard' .NET Framework 4 variety?
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Jul 26, 2010
I actually came from VB6 and starting to learn VB.NET. I saw this line of code which I cannot understand how it works nor how it goes.
Private MAX_VALUE As Integer = (1 << 14)
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Dec 7, 2009
I am now facing the part II confusion with dll files. I would wanna load a custom built unmanaged dll that someone completely built, and load it within Visual Basic. I cannot reference it, because it doesn't seem to work. I wanna figure out how to use coding to load those dll's. Here is what I mean. If you have heard of irctunes. I can control itunes the way I want mostly using a dll. Here is the link to download the whole zip: URL] There is irctunes.dll which is unmanaged. I would wanna load it with Visual Basic. I cannot reference. There is an html file. It tells you the functions and parameters. I wanna access the functions that are within the dll file.
[Code]...
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Dec 16, 2009
If Class X is within the scope of Class Y, is X a subclass of Y?If Class A is a sub Class of B, then is Class B considered a super class of A?if Class C inherits Class D is Class D a superclass or parent of Class C?if Class E extends Class F then we can consider Class E a child of F?if Class G inherits Class H and is within the scope of Class I then who is the parent of Class G? Classes that inherits Class J and classes that are within Class J are all sub classes of Class J?
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May 30, 2012
We can declare a byte variable like this, for hex '88'
Dim bytes = New Byte() { &H88 } My case, 88 is assigned to a variable, hexvalue
How to declare the byte with the variable hex value?
Dim bytes = New Byte() { &H & hexvalue }the above throws syntax error.
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Feb 19, 2011
I'm trying out a program which I found on the net. Why is it necessary to put to curly braces at the end of the statement? It gives an error: "Byte has no constructors". Dim data As Byte() = New Byte(1023) {} I can't put the code like this either, it produces the error "byte cannot be a 1-dimensional array".
[Code]...
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Apr 12, 2011
I've been testing the code below (vb 2010) and everything works except for the fact that I cannot get the statement "Dim dirName As String = Path.GetDirectoryName(Application.ExecutablePath)" to work. The dialog is "Path is not declared.it may be inaccessible due to protection level".As you may note I have it commented out below and went with the more explicit statement. Note that the code is from another author and I'd like to understand how to make this work as originally provided.
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
Dim fileName As String = "flatfile.txt"
'Dim dirName As String = Path.GetDirectoryName(Application.ExecutablePath)[code].....
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Apr 21, 2009
I have an application that I need to declare a new reportdocument. I try to do the following statement: report = new auditReport and it tells me that the auditReport is not defined. Even though I added the report to the project. I tried to do it in another application and it works fine.What could be wrong with the application that doesn't find the report I added to it?
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Mar 29, 2012
if this silly but I am trying to declare a string variable by the following line
[Code]...
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