(2005) Arrays Of Structures Within Structures?
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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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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May 24, 2009
I'm currently doing this project where i have to create a program that let's the administrator manage students (and their tests.) I have decided to use Random Access file in this project.because structures will need fixed lengths...i don't know how will i search through the students (a function of the program) when each student structure has a different length because of the number of tests they've done.* I have created a variable in the aStudent structure so that i can know the number of tests a student has done...but don't know how to use it.
Public Class FormAdmin
Dim currentStudentName As String
Dim currentStudentID As Integer = 0
[code]....
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Jun 18, 2011
I have created a structure as below. I want the structure to be an array...so I can use a call like picks(1).a or picks.a(1) = blah blah. I don't understand how to use an array of a structure..
Public Structure apicks
Dim a As String
Dim b As String
End Structure
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May 22, 2011
what is the best way to add, delete elements from arrays of structures structure
vb
Structure Proxy
Dim Server As String
[Code].....
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Mar 14, 2010
I would be more that happy for someone to tell me I am missing something very simple here I am writing code that - amongst other things - talks to code on other servers using the tcpclient function in .net
What I want to do is - in essense very simply. I want to define a structure which includes an array load it with data and sent it to the other end of the socket.
[Code]...
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Nov 15, 2011
I want to create a relational database in VB2010 and I am attempting to accomplish this goal by creating a structure of records to be stored in a Random Access File.For each record, I want to organize each fixed-length record so that 4-integer sets of data are stored into a a multi-dimensional array.But when I try to write the code below at the module level, I get an error.
Structure PictureDat
'len= needed for Open
of Random Access File [code].....
Since I want to read/write/save the data in this structure to a Random Access File with a fixed record length size, I need to exactly specify the size of the record...which is, of course, determined by the array's dimensions.If I could accomplish this strategy, then I could search this random access file for a match of search criteria consisting of 4-integers with any of the 4-integer sets of data in each record and thus find, edit, delete and search records...therby retrieve information from my database.
Is my program design inefficient? Is there a better way to handle perhaps hundreds of thousands of records? The IDE keeps telling me that I am using a deprecated method of file I/O when I use FileOpen(), FileGet(),FilePut() and should be using MyFile.I am entirely comfortable with my time-tested method of data storage that ensures the security of disk storage while exposing only one record at a time to the PC's volatile RAM, thereby not allowing all my data exposed to possible memory corruption on a PC left on for hours, which would be the case if I loaded the whole file as a monster- sized string or stream. Also, these older file access methods allows my code to run on PC's with modest amounts of memory.
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Jan 29, 2009
I have to make this program to keep track of product description, ID, price, and quantity. I am manually coding some and the user can input products as well. I want to display the product and it's ID in a listbox and put price and quantity in seperate labels. [code] My question is how do i keep the array index numbers sorted so when i click an item in the listbox it will show the price and quantity in the labels for them?
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Feb 16, 2009
i am currently running a program that will allow me to save all data on the form to open and edit at will. It uses a structure of 8 arrays, each with 16 values to save the information.
When i try to save the text into the array, it tells me that its a bad record length and crashes.
Here is the
Public Structure save_weekly
<VBFixedString(8)> Public dates() As String
<VBFixedString(30)> Public description() As String
[Code].....
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Nov 10, 2010
I have the following code... in an MDI application. [code] Various lines of code which put data into the Myinstance and then save the instance into the ArrayList.I have buttons which run procedures and functions in the formchild and also in the Class1. I need it so you can jump between formchild instances, and when you do so and click a button on that form, it will run the Class1 code but using the data in the arraylist and myinstance that was set previously by the selected formchild. Then if you switch to another child it uses data from this form. Can this be done by declaring the arraylist with more dimensions and then refer to the records with the index of the selected form instance, e.g.Selected Child is index(3)
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Nov 6, 2010
I have created an MDIparent form and a MDIchild. There is a button on the parent which makes multiple 'clones' of the child form, each time its clicked.I also want (maybe with a module) a set of variables, and array of a structure but these are available to each copy of the child, but each copy's variables, arraylist etc contain its own data?Therefore if you select child1 the variables and array will have different data to child2, child3...etc...
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Sep 29, 2008
I have written a ActiveX DLL in VB 6 which is like -
[Code]...
When I do this everything works fine and I am able to pass value to dll. I am passing two structures arrays and other single values like int and double etc. So far so good. But when I insert this code in another application (created in same vb.net 2005) where I actually intent it to use then i get the following error -
System.Runtime.InteropServices.SafeArrayTypeMismatchException
Specified array was not of the expected type.
I am puzzled as to why is this happening. I checked basic settings and they are same. In short the code works if i create a new project and go on but does not work and gives error if I insert in an existing application's code where i wanna use. To test I created a dll without passing structure arrays and then it worked in that application.
[Code]...
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Jun 27, 2012
I'd like to give a homework assignment to a person learning VB.NET. I'd like it to use basic inheritance and a variety of data structures including queues, lists, arrays, or stacks in a windows forms application. I was thinking of a pizza-ordering application. This would allow them to utilize some basic inheritance and practice using .NET UI elements.
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Aug 23, 2011
I am in the process of writing a tool to manage DHCP servers using the DHCP Server API. Its an unmanaged DLL so using it is a PITA at least for me it has been.Currently I am stuck trying to enumerate the IP ranges in a particular IP subnet. I am able to access an array of structures but I have only been able to access the first structure in the array of strucutres.Using this I can sucessfully access the first structure in the array.
Dim element_info_array As DHCP_SUBNET_ELEMENT_INFO_ARRAY
Dim element_data_ptr As LPDHCP_SUBNET_ELEMENT_DATA
...
element_data_ptr = DirectCast(element_info_array.Elements, LPDHCP_SUBNET_ELEMENT_DATA)
However when I use this to try and loop through them one at a time it does not work. The ptr returns 0 is null.
Dim element_info_array As DHCP_SUBNET_ELEMENT_INFO_ARRAY
Dim element_data_ptr As LPDHCP_SUBNET_ELEMENT_DATA
For i = 0 To size
[code]....
The sizeof for DHCP_SUBNET_ELEMENT_DATA could be off due incorrectly setting up the union structure for it. I was not sure how it define it so that only the first ElementType and one of the other components is avalible at any given time. It wont even read the first pointer though so that has not even come into play yet.
<StructLayout(LayoutKind.Sequential)> _
Public Structure DHCP_SUBNET_ELEMENT_DATA
Public ElementType As DHCP_SUBNET_ELEMENT_TYPE
[code]....
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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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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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Mar 28, 2010
What is the different between these 2 structures?
Structure INPUT
Public dwType As InputType
Public mi As MOUSEINPUT
Public ki As KEYBDINPUT
End Structure
[Code]...
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May 14, 2011
Structure TextureStruct
Dim unk1 As ULong 'always 0x70007
Dim unk2 As ULong 'always 0x70007
Dim unk3 As ULong 'always 0x70007
Dim unk4 As ULong 'always 0x70007
Dim unk5 As ULong 'always 0x70007
Dim unk6 As ULong 'always 0x70007
[Code]...
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Jun 5, 2010
Is it possible to declare a new list inside a structure.
I'm trying to get a list of structures that each contain a list of points,
but when i try to declare a new list inside the structure VB says "keyword not valid as an identifier"
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Mar 8, 2010
I have been trying to read the cd toc in one go from the API, I can read it OK with a single byte array, but I can't find a way to fill the formatted arrays
Code:
'ORIGINAL STRUCTS
'MAXIMUM_NUMBER_TRACKS = 99
'typedef struct _CDROM_TOC {
' UCHAR Length[2];
[code].....
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Jan 21, 2010
I am currently working on a project for myself which looks through employee's information to find their availability to work. I've tried making a structure which holds the employee's information but I can't think of a good way to create different instances of it and store information in it at runtime. I'd prefer to load the information in at startup and not have to declare each employee and information. I am very new to Visual Basic 2008 but I have a good grasp of arrays from C and C++.
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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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May 1, 2012
lets say its something like[code]...
i want to add a function like this inside the structure
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Nov 7, 2009
I have a Structure, and I am having trouble initialising it. Specifically when I try to populate the Vector3 variables, it tells me that they are Nothing, so I need to make them New when the array of this structure is declared.[code]Structures cannot declare a non-shared 'Sub New' with no parameters.I have no parameter to supply, and this will be an array so I'm not even sure how I would supply it.The second option to fix the error is to make the Sub New shared, but then I get other errors: Cannot refer to an instance member of a class from within a shared method or shared member initializer without an explicit instance of the class.Does anyone know how I can resolve this. My end goal is to have an array of this structure type with the Vector3s ready to use.
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Mar 10, 2009
I have created a collection of structures. Each structure, of course, contains fields.
Lets say something like:
Public Structure clientStructure
Public ID As String
Public firstName As String
[Code]....
How can I access a field of a particular structure using for.... each?
That is, how can I retrieve out of the collection (lets say item 5's) firstName, using for...each?
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Sep 1, 2009
Can a list class in vb.net contain Data Structures ?
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Jul 26, 2009
Just a little frustrated with a simple error in a listbox result on a mobile application.Here is a sample of the results I should be getting:
The inputs are 50mph & 4.5 hours
Hour distance
1 50
[code].....
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Feb 21, 2012
I need to have an Array of UDTs(Structures). Elements have to be added (at end) and removed (from anywhere). The different values of the elements need to be changeable.
I know how to implement it as an oldstyle array, but wouldn't it be better to implement as a List ( of T)? and if yes is such a procedure possible?[code...]
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Mar 16, 2011
It says that I can't have structures as optional arguments.That's really annoying for my program. Isn't there any way to circumvent this?
Sub fa(Optional ByVal colz As System.Drawing.Color = Color.AliceBlue)
End Sub
This example cannot compile
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Aug 4, 2011
I have an interface IDigitalState defined as
Public Interface IDigitalState
ReadOnly Property Code As Integer
ReadOnly Property Name As String
End Interface
[Code]....
What I wanted to do was declare a variable as a nullable type of IDigitalState. I understand why I cant do this because the interface may be implemented by a class which is not allowed to be nullable. Is there a way to define the interface so that it can only be implemented by a structure.
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