Structure Inside Another Structure Receives Null Reference Error?
Jan 5, 2012Module Module1
Public Structure structure1
Public TRANS() As structure2
End Structure
Public Structure structure2
Public X() As Integer
End Structure
End Module
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Class Structure - Large Structure That Has Lots Of Properties ?
Jan 5, 2010I'm new to VB 2008 after having spent a long time with VB6, so I apologize if this is a stupid question. But I'd really like to have this straightened out.
Let's say I have a pretty large structure that has lots of properties.
Code:
Now say that I want an internal database with about 10 instances of this structure total, describing, say, 10 different products that a store sells. When these values are loaded from a database, they remain totally static. (However, they can be different each time a program loads)
Now say that I have a class. Each instance of this class is a type of that BaseProduct structure. Meaning, each instance of the class pertains to one of the 10 types of products that the store sells. However, this class has additional properties that pertain specifically to each instance, which are not static.
Code:
Now, the problem here is... If I have 200 different transactions, each one contains an instance of BaseProduct. BaseProduct is HUGE, and is largely redundant (only 10 types possible), so I think it's a little silly to include a whole copy of it with EVERY transaction. However, the Transaction class really needs information regarding the base product it pertains to. Is there a way to, instead of declaring a New BaseProduct in the Transaction class, to simply make one of the properties of the Transaction class a pointer to a BaseProduct variable?
In VB6, I would accomplish this by making a BaseProduct(10) array, and then giving each Transaction an ID number referring to an entry in that array. But in VB 2008, using class structure, this is impossible. I can't define the BaseProduct(10) array outside of a class in a namespace, and if I define it in the actual application's form, then the class loses modularity since it relies on the application that's using it.
Converting Structure Within Structure To Byte Array For Socket
Aug 29, 2009I am trying to communicate with an external device and i am trying to send a byte array to the external device via sockets but i am always getting a response the message size is too small so i am not sure what i have done wrong. Between the data type there should be no alignment present and all numbers are represented in little endian format. The char array is not null terminated as mentioned in the protocol specifications.
I have to send data based on a struct that embeds 2 other struct. So here's my vb.net code for the struct used to convert to byte array and the sending part.
Public Structure MESSAGETYPE_OIP_Login
Dim Header() As COMMANDHEADER
Dim UserName() As PSTRING
[Code]....
Using An Array Inside Of A Structure In VB?
May 17, 2012I'm trying to create a structure and inside it put an array of "Genres". This is my structure declaration:
Structure BookData
Dim strGenres() As String
[code]....
But I keep getting an error with the .strGenres(5). VB is telling me "End of statement expected"
Invalid Structure Size When Marshalling C Structure To .NET
Apr 14, 2012I'm experiencing a problem with the following c-structure:
typedef struct tagTEXTUREPROP
{
DWORD dwSize;
[Code].....
The Marshal.SizeOf obviously calculates a size of 76 and it works with the DLL function, but it leaves me with some bad feelings.
VS 2008 Convert The XML Structure Into A Class Structure?
Apr 25, 2010I'm having a problem that's driving me crazy; I can't understand how to convert the XML structure into a class structure (that I want to use to hydrate a XML document).
The XML document looks like this:
xml
<?xml version="1.0" encoding="utf-8"?>
<artists xmlns:opensearch="http://a9.com/-/spec/opensearch/1.1/" xmlns="http://www.spotify.com/ns/music/1">
[code]....
Enum Inside Structure - Adding Properties?
May 19, 2009I have an enum that I want to give some methods. I thought about changing the enum to a structure so I could add properties, but then the enum is a value inside the structure (not the structure itself), so this would affect comparisons and such. (For example, instead of writing
EnumVariable=EnumConstant,
Now it is
StructureVariable.EnumValue=EnumConstant).
At least, this is my understanding of it. It seems awkward to have to do this for such a simple scenario, so is it possible give enums properties, yet still have them treated as before? I've thought maybe I need to create a new valuetype from scratch, but I've never done that before.
Return Values With Reference Arguments Or By Structure?
Jul 10, 2009In what situtations is it best to use reference arguments to return values?
Sub Example(byref value as integer)
value = 3
End Sub
In what situations is it best to return the value (perhaps in a structure for more complex types)?
Function Example() as integer
return 3
End Function
Side Effects Of Defining A Structure Inside A Class?
Jun 6, 2011What is the side effects of defining a structure inside a class (name it X), and create a property inside that class of the type X?
View 1 RepliesAnother Method To Reference The Array And The Member Of The Structure To Get The Data?
Jan 31, 2010I have problems with array of structures.my structures are like this
structure order
xxxxxxxxxxx
yyyyyyyyyy
zzzzzzzzzzz
end structure
and then I created many array of structures, like this private arrayorder (100) as order
now i need to sort the entire xxxxxx member of the array of the structure with a function, but I dont want to use loops with arrays indexes to access the information. I want to know if there is another method to reference the array and the member of the structure to get the data.
Structure Hold Small Number Of Reference Types?
Jun 10, 2009Is it okay for a structure variable to hold a small number of reference types? I thinks it's fine because the pointers themselves are not that big, regardless of what they're pointing to. But I never did fully figure out the whole heap/stack thing, so I'd like to make sure.
View 6 RepliesVS 2005 Reference A Member Of A Structure By Using A String Variable
Mar 20, 2009, I was wondering if it was possible to reference a member of a structure by using a string variable. Here's an example of what i'm talking about:
[Code]....
Now, I know that you would usually reference the value in any of the members by using the following (String1 in this case)
[Code]....
Arraylist Of Structure Within Array Of Structure?
May 23, 2010I want to make a structure within a structure. Basically it will appear like this:
Structure ID
dim CardType as string
im CardCode as string
[code]......
Assign Array Of Structure To Another Of Same Structure?
Oct 12, 2010In Vb.net I am trying to assign an array of structure to another array of same structure[code]...
View 2 RepliesStructure Error
Mar 11, 2010hello
I would like to know if it is possible to store an array within a structure. For examples for recording people with more than one name. Like this:
Structure Product_Reccord
Dim PNames(3) as string
end structure
It is giving me an error, help please!!
Error Validation With Structure's?
Feb 23, 2010I am writing a program using a structure for the first time. The structure has 10 string variables declared inside each equal to a individual textbox on a form. I need the program to be setup so that if one or all of those textboxes are empty at the time of the event being activated a messagebox is displayed telling the user one of their textboxes is blank. Now i could do this in a series of 10 if then statements im sure but using a structure theirs got to be an easier way.
View 5 RepliesStructure With A Structure Array?
Sep 12, 2011I have two structrures
Public Structure PhoneScheduleEntries
Dim Count As UInteger
Dim PhoneSchedule() As PhoneScheduleEntry
End Structure
Getting Error When Trying To ReDim Array Structure
Jun 27, 2011This is my structure...
<Serializable()> _
Public Class AcctRecords
Public Amount() As Long
Public DateC() As String
[Code] .....
This is where I try to create a new instance but I get an error that states:
Overload Resolution Failed Because No Accessible "NEW" accepts this number of ArgumentsPrivate Sub FixMasterArraySize(ByVal Cnt As Integer)
ReDim Preserve Acct.Master(Cnt)
For I As Integer = 0 To Acct.Master.Length - 1
Acct.Master(I).AcctType =
New String
Next
End Sub
If Acct.Master(I).AcctType was a Boolean type there would be no error..
Accessing The Property Inside Dynamic Control Gives Null Reference Exception?
Jul 13, 2010I have an app with 24 different Forms. They have some security options based on which the 5 different buttons Submit, Approve, 2nd Approve, 3rd Approve, Reject etc get enabled disabled.Now I designed a MainForm that has all the buttons and the security code for them. I have created eachform as a usercontrol and load them dynamically based on which form the user wants. My loading works perfectly fine. I load the control and Add it to the place holder in the Page load event of the main page.
Now when the user selects the Submit button I want to call the Save method inside the usercontrol of the Form as each form will have a separate Save. So when I try this code snippet I get the Null reference error. Do let me know how to resolve it.
Private UCDynamic As UserControl
Then on Page Load event I use this code
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
If not Me.IsPostBack
UCDynamic = LoadControl("Controls/BkCode.ascx")
Me.PlaceHolderForm.Controls.Add(UCDynamic)
End if
Then on the ButtonClick Event for Submit I do this
Protected Sub Save_OnClick(ByVal sender As Object, ByVal e As EventArgs)
Save()
End Sub
[code]....
Thats where I get the cast Null reference error. So is it that after post back the control no longer exist on the page.
Error Handling & Copying Folder Structure?
May 2, 2011Below is a tiny program I modified from an example Microsoft code tutorial. This program simply copies .flac and .mp3 files from one specified folder to another, and if the file is already there it simply does not copy the file. I would like to make 2 changes to the program:
How would I go about making the error handling work (i.e. not crashing the program when an invalid input is made)?Also, a big change I would like to make would be for it to copy the folder structure and all files in the original folder (At the moment, it only copies files that are directly in the original folder, not files that are in folders inside the original folder).
[Code]...
Error In Passing Structure Array To Function
Nov 7, 2011I'm a beginner when it comes to Visual Basic coding and I need some help with an error I'm getting. I'm trying to pass a structure array to a function to figure out a student's grade. I'm getting the error that 'QuizOne' is not a member of System.Array. Here is my code:
[Code]...
Creating A Child Class Of XElement That Still Keeps A Reference To Original XElement And Preserves Tree Structure
Dec 20, 2010I'm working with a class that inherits the XElement class.The new class is called MXElement.It adds some new functionality to it for navigating through the XML tree, as well as some more information regarding attributes, but that's not particularly important.My problem is that I have an XML Tree filled with XElement objects.However, when I create a new MXElement object from the XElement object before, it is just a copy of that object. This means that any changes that I make to this object will not effect the original tree.I suppose what I'm asking for is a way to build in the functionality for my MXElement class and keep references to the original XElement objects.If possible, I would really prefer to keep MXElement a child class instead of building a lot of extension methods for XElement.
View 1 RepliesCreating Array Of Structure Type - Marshaling Error
Jul 23, 2009I have to create an array of structure type in VB.net. but I am getting error while marshaling this error. I have to pass this array of structure type in to Dll function.
Code:
Structure declaration:
<StructLayout(LayoutKind.Sequential, CharSet:=CharSet.Ansi)> _
Public Structure dx_entry
<MarshalAs(UnmanagedType.ByValTStr, SizeConst:=10)> _
Public dx As String
[Code] .....
I am getting the following error:
An unhandled exception of type 'System.ArgumentException' occurred in Audit_Demo_2307.exe
Additional information: Type dx_entry[] can not be marshaled as an unmanaged structure; no meaningful size or offset can be computed.
Print Structure Array Variable Contents - Error?
Feb 6, 2012I have a structure named StudentData, it consists of a studentname, an array of testscoresand the student average. There is also an array of structure objects for a total of 6 students. I have the header, column heads, the student names and the averages printing when I click the print page event. I have tried multiple ways of setting this up to get the test scores to print, these are the structure array variables. When I put in the code to process the arrays testscores, I receive a run time error that I don't understand
View 2 RepliesVS 2010 Structure Of Lists - Object Reference Not Set To An Instance Of An Object
Oct 16, 2011I am struggling with the following - I try to add a value to a list, where the list is defined in a structure.
[Code]...
Structure Statement (UDT) And Object Reference Not Set To An Instance Of An Object
Feb 12, 2009I am using asp.net with vb for my scripts.I want to use an array of a Structure to store data parsed from an xml file.[code]All appears to work fine until I add the code that is in bold, I then get the Object reference not set to an instance of an object.
View 6 RepliesXML Null Reference Error?
Jan 4, 2010Im trying to write code that will insert 'records' into an xml file, but everytime i click the button to make the changes to the XML file, it throws a null reference exception, ive gone through this code must be 100 times and cannot find what needs to be declared as 'new' as i know nodes can't be 'new' and the doc is 'new'
Imports System.Xml
Public Class frmuseradmin
[code]......
Asp.net - Structure A Class Inside A Class?
Jun 3, 2011Currently, if I have different classes containing functions etc, I would structure them all in the 1 VB file titled whatever the main Class is. For example:
[Code]...
However, the problem with this is the file can become 1000s of lines long making hard to find portions of code. Is there a way I can store SubClass in a file such as MainClass.SubClass.vb so that its easier to locate classes? Or is there a better, more standard, way of doing this?
VS 2008 - Null Reference Error
Sep 18, 2009I am testing a program, and I am getting a null reference error at this line. oParent.Invoke(oParent.cUpdatingSolidWorks, iSolidWorksItem). I have stepped through the program, and all the items are created. A watch window with the three objects all have data in them. I am wondering what would cause this error if the objects exist. [Code]
View 5 RepliesReference Structure Element By Element Name?
Jun 7, 2011I want to be able to reference an element in an array of structures by the name of the element in a visual basic 2010 function. For example
Public Structure myStruct
Public element1 as string
Public element2 as integer
Public element3 as boolean
[code]...
Is it possible to reference a structures element by the element's name in a similar way to that shown above. The code shown above does not work, as the expression obj(i).[elementName] does not work as hoped.