VS 2010 - Classes Vs Structures?
Dec 11, 2011
For the time being I have been using a Structure to store "people" (their name, gender, age, etc...), because I really love to refer to something like Mike.name or Caroline.age, so I could simply put Caroline.age += 1 anywhere in the code and here you go, Caroline is one year older. No more simpler.But because of how inflexible (compared to Classes) Structures appear to be, when I needed to iterate through all the instances I was forced to use a list or dictionary so I could use a FOR EACH ... NEXT block. That was resolved by you people in the previous post, but I'm having the problem that I couldn't use the elements of the list to change the original instance of the Structure proper... I mean, if I code something like this...
For Each thisperson As Person In peoplelist
If thisperson.name = person_selected Then
'person_selected is the SelectedItem.ToString of a listbox[code]....
Well, I thought that thisperson.teamleader and Mike.teamleader were going to be equivalent (when the IF statement was true, that is) but that doesn't appear to be the case. So right now I'm really hating Structures...But when I look into Classes... well, they have more flexibility, yes. You could construct a FOR EACH block without any other trick like the "on-top" list, and that it's very useful indeed, but (a big "but" IMHO) I lose that NICE feature that makes possible to write the name of one of them instances like Mike.age or Caroline. kills
I mean, if I wanted to add a year to Mike, well... there is no "Mike" in the first place. A "Mike" string could be a property for the class, but I cannot (or know) magically refer to him with the ease of a Structure, so when I want something so simple as Mike.age +=1 ...well, with a Class I'm simply clueless to how locate him and change ANOTHER property of him.I suppose I am doing something very wrong, because I cannot believe VBasic could force on you those two extreme philosophies...:
Classes = +flexibility -usability ???
Structures = -flexibility +usability ???
What I want to do is SO simple that I cannot believe I need to choose between the two.
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Oct 23, 2010
I know that Structures are value types and classes are reference type, i know that since structures are stored in stack they are faster to use i also understands that structures can not use the Inheritance concept but still in most examples i see i always see that the authors use classes when building something like BBL library, if structures is light-weight compare to classes and i don't need it to be inherited should i use structure instead of class?is there a rule of when to use class and when to use structure ?
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Feb 3, 2011
I've been programming a custom structure to use in my program for a while now and I am debating whether I should switch over to using a class instead. Reason being is because I've read from a few sources that structures should be kept for simple storage of primitive types. However, I am using my structure to store a few integers and a few custom classes of my own.I haven't noticed any slowdowns or performance issues but I do know that I have to update the actual variables in the structures since they are value types and not reference types.
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Aug 21, 2010
I've heard bad things about overusing regions but when adding enums to my classes I put them into a #region "Enums" at the end of the class, and do the same with structures and even subclasses.
Is there a better/standard way to go about grouping such elements on classes?
(Note: this is tagged C#/VB but maybe the same situation exists for other languages, like Java)
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Sep 27, 2009
I have tried this question several times, sometimes a little in the face of MS VB teams but with no constructive answers. Perhaps with too much rant. I suspect that VB.NET does not allow me to do what I can easly do in VB5.0. The VB team should easily be able to supply the information I need, but have not yet answered the questions. I want to do a lot of work on very large bitmaps (20 Mp or more; 80Mb or more ARGB) using arrays for access. This I used to do in VB5.0 using the SAFEARRAY and BITMAP STRUCTURES. NOT the corresponding .NET CLASSES. But I now need to use an SDK requiring .NET. However, through lack of wisdom, the VB team dropped 5 critical resources on the move to VB.NET - VarPtr, VarPtrArray, the 2 structures and CopyMemory. The SAFEARRAY CLASS seems to lack a set method for array data and the BITMAP CLASS seems to lack both get and set methods for data. On building a .NET solution using VB.NET, c#.NET and C++.NET projects I could not locate the set and get methods. Interop could not upgrade my VB5.0 to VB2005 - presumably on account of these 5 problems. I was surprised that even C++ suffered too. .NET hurts. So, first off, two critcal simple questions: A) Bearing in mind that much of the .NET is tinsel-wrapped APIs, does a pointer to an array still point to a defining SAFEARRAY STRUCTURE of the original format (NOT of course to a first element of an array). If that is so, I am lucky for I can then fill and use (perhaps) my own SAFEARRAY STRUCTURE by memory manipulation in C++. B) If the same applies to a bitmap pointer I can then perhaps do the same with BITMAP STRUCTURES. If that can be done I can hopefully work in a .NET solution containing C++ (for the pointer and mmory work) and VB2005 (for the rest of the work). I can then 1) in VB define two empty byte-arrays GLOBAL in VB.NET- Pic1() and Pic2(). They do not need to be dimensioned. SAFE FROM GC 2) in VB define two GLOBAL SAFEARRAYS to match the arrays, one with one and another with 2 dims matching the bitmap in size. SAFE FROM GC 3) move ByRef the 4 objects to VC++. STILL SAFE FROM GC, LEFT EXACTLY WHERE THEY WERE. 3) copy the BITMAP data pointers to the data pointers of the SAFEARRAYS. DOES NOT MOVE ANYTHING. 4) copy the addresses of the SAFEARRAYS to the corresponding arrays STILL DOES NOT MOVE ANYTHING, BUT JOB DONE. And then I will be able to process the images in seconds rather than minutes after moving only 4 4-byte numbers. I would welcome alternative sequences, provided they DO NOT involve put and set pixels or array elements on the trivial side and do not involve moving 80Mb of image data between "safe" and "unsafe" memory on the Herculian side. Else, as the Pic() ans Safearrays MUST point somehow to structures, WHAT EXACTLY ARE THEY, AND WHERE? I want to access them. If I can't overcome these 5 silly MS blunders I'll just have to build two uncoupled projects - one in VB5.0 and the other in VB/VC++ .NET. I'm not going to get involved myself with tinsel and gladwrap workarounds.
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Jun 13, 2012
How can I structure my classes so that the user interfaces though a single class while the supporting classes are hidden from their view? I think its best understood in an example:
Public Class MyInterface
Public Economic as EconomicClass
Public Sub New()
MyBase.New()
[code].....
So you might ask why am I even separating them? It's strictly for others who will be working with this interface. I need to funnel them though a logical structure:
interface.Economic.MyMethod
interface.Currency.MyMethod
etc
This way everything is already handled for them in the background and they only need to run the method they need. I don't know if I can have it both ways in VB.NET.
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Oct 24, 2009
Here is some example code of what I mean:
vb
Public Class Form1
Private Sub Button1_Click(ByVal sender as Object, e as systemEventArgs) Handles Button1.Click
[Code]....
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Sep 15, 2011
These are the instructions. Create a Visual Basic program that reads in baseball player information from a form and holds all of the player information for an entire baseball team (20 players). A baseball player consists of a first name, last name, number, position, and batting average. The form should contain 3 buttons Add Player, Display Players, and Exit.
[Code]....
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Dec 7, 2010
I have built a webservice to take order information..
[Code]...
My clients use the code above to enter multiple orders without any issues, but I need to be able to add multiple Products to each of the orders. I cannot figure out how to add the contents of the Product Structure into a GenericList, within the OrderList.
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Jan 20, 2009
I have a structure called 'Scheme' and in my program I want (ideally) an ArrayList of 'Schemes' (so i can add, remove schemes etc.). However, within the 'Scheme' structure, I want to have an ArrayList of 'Item''Item' is another structure. Are there any solutions out there for iterating through these arrays quite easily?
How can I easily add multiple Items to a Scheme and mutliple Schemes to my Scheme array. Code is below. When I try to add Items to a Scheme, I get the 'Object not set to a reference of an object, try the 'New' keyword', but you cannot declare 'New' keywork within a structure.
[Code]...
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Dec 10, 2011
I have a public structure in the same form I'm working with, like this...:
Public Structure Person
Public name As String
Public age As Integer
[Code]....
At the start of the code I've declared some 'Person' instances...:
Public TeamMember1 As Person
Public TeamMember2 As Person
Public TeamMember3 As Person
[Code]....
I don't know what to put at ??????. If we were talking about control objects I would write Me.Controls("TeamMember" & n) and that would work. But with a public structure I don't know how to refer to it.
Is it even possible? And if not, how would you do what I'm trying to accomplish?
I only want to run that 'If' statement with every team member which I have, and right now the only way I know to do it is to create 10 (!) of those 'If", and only change the team member number at the end. And that's horrible...
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Dec 10, 2010
I save data entered by user into a structure like this
[Code]...
Q1. How can i save that structure into file using binary read write methods.
Ans. [URL]
Q2. How can i save that structure array into file using binary read write methods.
Ans. link to some other tutorial or resource if u know
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Jun 2, 2010
I read in the Book "Mastering Microsoft Visual Basic 2008" about "User-Defined data types".The example given is creating a Structure as follows.I wanted to check that so I wrote all the code given; I used a TextBox and a Button for this.(I didn't include the "CheckDate" here; that is in the book)
Structure CheckRecord
Dim CheckNumber As Integer
[code]....
The problem is this does work.What I get is "00000". and I found out that the "Checks(4)" Array does hold any value ie: on keeping the cursor over that, it shows "CheckAmount 0.0, CheckNumber 0 , CheckPaidTo Nothing ".
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Jun 28, 2011
I need some help with how to organize classes in VB.NET. I have a class called parent with methods for adding, deleting etc. But I also need a method that returns a list of all the parents, a list with parent objects. Where do I put this method? Do I put it in the parent class or do I need to make another class called parents?
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Oct 16, 2011
I've seen people discourage other from using nested classes, because the make things more complicated and are evil and whatnot.But I want to know what possible justification there would be for using a nested class and if there are any possible benefits for using them(or structures for that matter).
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Oct 21, 2010
Public Class Form1 Dim CharList As ArrayList Private Sub btnAdd_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnAdd.Click CharList.Add(TextBox1.Text.ToUpper)End Sub Private Sub btnClear_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnClear.Click
[Code]...
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Jan 23, 2012
I have two classes, one nested in the other. [code]Neither "Name" or "ID" are unique between operations and records.I wish to construct a dictionary using LINQ = Dictionary(Of String, Of List(Of Integer), whereby the keys are uniqe examples of Names in my collection and the values are the collective set of distinct IDs that are associated with those names.
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Nov 16, 2011
For a class project (online course, no instructor handy to get a quick reply from -_-) we are to write a short program using classes and OOP to roll a pair of 6-sided dice 1000 times and count the number of times the total of the two dice is 7. Easy enough, and I've read over a few examples that people have written, but they don't seem to use OOP. I'm not asking you guys to do my homework for me, but I am terribly lost when it comes to using OOP. So far I understand that I should be using a Random() class object to determine the roll itself, and then maybe load each roll into an array and use a loop to check if each element is 7 or not, and then increment a counter? How do I set the range of Random() so my dice rolls are representative of a 6 sided die? It's all a bit overwhelming and I'm not sure what I should do next.
[Code]...
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Feb 24, 2011
What are the best ways you guys recommend to search the MSDN Code Library. I know there have been several instances in searching for ways to do something, doing a long workaround, and finding out later that there was a built in class that handled the problem that I was working on much simpler.
So what are some of the ways you guys use to find tools, classes, etc. when coding. Or are you just that awesome already.This is kindve just a general tips and tricks question. Sorry if Im in the wrong forum mods.
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Oct 26, 2011
Is it possible to have multiple classes in a namespace and be able to reference the functions within the clases if the Major class is instaniatated from another class?? for instacnce:
Namespace Database
Public Class Data
Public Class Prepare
[code]....
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Mar 30, 2011
I have a MDI application and a very complicated class there which populates its properties from a dataset derived from an external database. Each form, including child forms have to be able to access that class and use its properties thorughout the whole session.I don't know where to 'preserve' these property values within the application. I kmow many books etc. suggest not to use public variables but I really can't find a way to solve this other than to use a public variable (which is a list(of my custom class) in this case.
I have a separate class called PublicItems.vb and declared there my public variable as
Public Shared secuniverse As List(Of myCustomClass)Is there something wrong with the syntax because if I try to use the variable secuniverse in my main application class, I get the following exception:'sectoruniverse' is not declared. It may be inaccessible due to its protection level.
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Dec 5, 2010
I've been trying to do this for a while now.What I intend to do is that when I load a webpage in a class, i raise event to my form that the data is recieved.
[Code]...
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Jul 13, 2011
I have put together the following code to illustrate the problems I've been struggling with:
Public Class OuterClass
Private _OuterProp1 As Boolean = False
Public Property OuterProp1 As Boolean
[code]....
I need to be able to refer to outer class properties and variables in an inner class, and I need to have a variable in one inner class set in a different class. I've tried Public, Private, Protected, Friend and all kinds of combinations of them, and I can't figure it out.
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Jul 20, 2009
I'm attempting to create a list of structures that contains a list of structures. I can't seem to figure out how to properly allocate the object for the inner list of structures. I expect the outer list of structures to have a couple thousand entries and the inner list of structures to be fairly small at 2 to 10. Both lists will grow over time but the number of elements within the inner list will be constant for an instance of the outer list. Meaning, if an instance of the outer list has 2000 entries each of those will have the same number of elements on the inner list, say 4 entries.
Here is a simplified code fragment. This fragment makes no attempt to create the instance of the inner list "StructBlist" since I can't figure out where to put it. Tried "New List(Of StructB)" in the declaration as well as "Alist(0).StructBlist = New List(Of StructB)" but neither works.
Public Class Form1
Structure StructA
Dim FieldA1 As Integer
[Code]....
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Jul 26, 2010
Is it possible to have visual studio 2010 automatically add namespaces to classes within folders just like c#?
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Mar 20, 2012
I was just wondering how you can make classes import into your main Form.vb
Let's say I make a class with the following.
Public Class OtherStuff
Public Sub HideMe()
Form1.Hide()
[Code]....
How could I make the Form1.vb include the things that are in OtherStuff.vb.
All of the solutions that I have tried come up with the same error. Reference to a non-shared member requires an object reference.
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Jul 10, 2009
I m trying to raise Click event of Textbox explictly but I m getting "Derived classes cannot raise base classes" error.[code]....
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Mar 29, 2012
I am having this strange thing happen where I have a Module that contains multiple classes in my project. In the Solution Explorer, the module shows up as a Windows Form and if I double click on it to open it, it tries to open the Form Designer. What could be causing VS to think that it is a Windows Form instead of a module?
[Code]...
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Sep 24, 2010
so far i got
code
For Each item As Reflection.FieldInfo In GetType(NameSpace.ClassWithNestedClasses).GetFields
rtfAppend(item.Name & ":" & Tab & item.GetValue(Me))
Next
For Each item As Reflection.PropertyInfo In GetType(NameSpace.ClassWithNestedClasses).GetProperties()
[code]...
which gets me the simple string vars and properties of my top class, but how can i apply this to loop through all sub classes and get there vars and props?
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Oct 13, 2011
Searching the internet finds no less than 700 different ways and opinions to accomplish what I'm trying to do, and I would just like to know the simplest, most bullet-proof way possible.
[Code]...
I simply want to extract the string "bar," which is inside <hostName></hostName>I can do this easily enough with simple string functions, but I'd like to do it with one of the .NET XML classes/methods.
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