VS 2010 Converting Recursion To Iteration?
May 10, 2010
Is it possible to make this function iterative or must it be recursive?
The Function traverses a grid of x length and y height. At each point in the grid, it checks all of it's neighbors to see if they are valid, meaning they exist in the grid and haven't been used yet.
The function works in it's current form but I was wondering if an iterative version would be more efficient.
PathManip is a Stringbuilder, stores the path currently being manipulated. PathQueue is a List(Of String), stores all paths yet to be traversed.
IsPathAlreadyUsed is a boolean function that checks whether or not a specified point has been used in the current path.
Sub FindNeighbors(ByVal coords As String)
Dim x As Integer = CInt(coords(coords.Length - 2).ToString)
Dim y As Integer = CInt(coords(coords.Length - 1).ToString)
[Code]....
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Aug 15, 2010
I developed an app, tested on few computers and all seemed fine. But now, some people suddenly get an error, which I can't repeat on my computers. Part of the exception:
** Exception Text **
System.TypeInitializationException: The type initializer for 'NumoABC.functionsBurtuSummas' threw an exception. ---> System.InvalidOperationException:
The form referred to itself during construction from a default instance, which led to infinite recursion. Within the Form's constructor refer to the form using 'Me.'
at NumoABC.My.MyProject.MyForms.Create__Instance__[T](T Instance) in 17d14f5c-a337-4978-8281-53493378c1071.vb:line 180
at NumoABC.My.MyProject.MyForms.get_MainForm()
[Code] .....
The If Me.Created = False Then is because while the form is loading, some events fire the updatePersonDataHandlers() sub, but I don't want it to happen until form is fully loaded. In the module functionsBurtuSummas line 2
Module functionsBurtuSummas
Private f As MainForm = MainForm
I have many modules who work with the MainForms' controls, so I use a private variable f to refer to the MainForm.
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Feb 13, 2012
I've got a menu with checkable items that appears on two different forms, and I'm making sure the two forms always have the same check states, so Form1 would have something like this:
Private Sub mnuWarnings_CheckedChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles mnuWarnings.CheckedChanged
'when one of these is checked, the other should also be
[code].....
But that yields this error:
An error occurred creating the form. See Exception.InnerException for details. The error is: An error occurred creating the form. See Exception.InnerException for details. The error is: The form referred to itself during construction from a default instance, which led to infinite recursion. Within the Form's constructor refer to the form using 'Me.'
There definitely aren't any references to Form1 within Form1.It only occurs when I use CheckedChanged--if I use mnuWarnings.Click, it works fine. And it only occurs in Form1 (the main form); CheckedChanged works fine on Form2.
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Dec 18, 2011
I have created a simple application where I fetch questions from an Access database and store the answers to another Access database. I am not sure how many questions client would like to ask, so I can't hardcode that number.
So, column names for answers table (besides user information like first, last name and so on) will be a1, a2, a3 ... aN.
And finally the problem!
For testing purposes I have hardcoded saving first 3 answers like this:
newEntry.a1 = answers(0)
newEntry.a2 = answers(1)
newEntry.a3 = answers(2)
Now I would like to iterate through all properties based on count of "a-type" properties:
'aCount is number of "a-type" properties
For i = 0 To aCount - 1
Dim property As String
property = "a" & (i + 1)
newEntry.property = answers(i)
Next
Of course, above code does not work, it is just a pseudo-code idea that "should" to the same as my hardcoded example.
Is it possible to iterate through predefined properties of newEntry object in that manner?
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Jul 28, 2009
I have a class called Profile that has some simple properties and then it can have a collection of ProfileItem that again has some simple properties and then it can have a collection of ProfileItem (RECURSION). Now I am trying to generated a very simple save function using XML Literals that come with VB.NET (3.5).
[Code]....
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Oct 16, 2010
The code is from a text book.[code]SetProgress is referenced within SetProgress, I don't understand it.Is it a recursion call?
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Jun 21, 2012
I've tracked a recursion error down to one subroutine, So when my form loads, it populates some listboxes from a database; any one of these causes the error:
ListboxQuery("select sculptname, sculptid from sculptures;", CloseSculptList, "sculptname", "sculptid")
ListboxQuery("select distinct eventtype from events;", EventTypeList, "eventtype", "eventtype")
'etc, etc
And here's the subroutine (it's querying a MySQL database):
Public Sub ListboxQuery(ByVal queryText As String, ByVal resultObject As Object, ByVal resultDisplay As String, ByVal resultValue As String)
'queries the database for a 1- or 2-column list of values to display in a listbox
Dim myCommand As New MySqlCommand
Dim myAdapter As New MySqlDataAdapter
[Code] .....
The error is the standard recursion error:
An error occurred creating the form. See Exception.InnerException for details. The error is: The form referred to itself during construction from a default instance, which led to infinite recursion. Within the Form's constructor refer to the form using 'Me.'
This is weird for two reasons: One, as you can see, the subroutine doesn't refer to the form at all, so I don't see how it could cause a recursion error, and two, I wrote this subroutine almost a year ago and it only caused this error last week.
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Oct 20, 2010
I am trying to implement Selection Sort in vb.net using recursion. Problem is that I keep getting stackoverflow if the array I want to sort is 1000 elements. I can't find the problem. I don't know much about stack overflow or how to check it. From my research the problem could be infinite recursion but I check for that and exit the sub.Here is the main code:
Public Class SelectionSort
Inherits DefaultSort
Public Sub New(ByVal num As Integer)
[code]...
Everything should work as far as I know. It works on an array of 10 elements and an array of 100 elements.
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Mar 29, 2010
calculate the factorial of given number using recursion.input the number in textbox and show the
result in another textboxrajeev ranjan, on 29 March 2010 - 12:38 PM, said:calculate the factorial of
given number using recursion.input the number in textbox and show the result in another textbox.
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Aug 13, 2009
In my application I am selecting a folder path and then asking the user if he/she wants to display full path or file names only.
My problem arises when I want to insert the results in a datagridview. The datagridview has 2 columns:
column1 ----> shows file name
column2 ----> shows file size in MB.
with the below code I get the file name and then the file size on the same column one after the other
I want to show as follows:
File Name Size (MB)
sample.txt 1.2
myspreadsheet.xls 0.6
Seanie.bmp 0.8
What do I need to modify in order to achieve this?
Code:
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Dec 3, 2010
I have a situation where I have a hierarchy. I'm trying to use LINQ to get all of the items throughout the hierarchy as opposed to For Each loops. I spent some time looking for examples, but most where C# using lambdas, and I'm not quite sure I understand it. I'd like to try to get all of the Items for a specific system, the levels of items could be n-levels deep.
Code:
System
SubSystem1
Item1
Item99
Item100
Item2
Item121
Item3
SubSystem2
Itemx
Itemy
Itemz
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Dec 29, 2009
I got that little function(I changed the name of variables)
Private Function everythingLinked(ByRef myClass As cls, ByVal found As Boolean) As Boolean
If Not found AndAlso myClass.checked = False Then
myClass.checked = True
[code]....
I want to rewrite it so it would only be loop and no recursion and I'm currently lost?I'm passing a class to this function(with a starting value for found as false) to know if it is linked to the middle of the tree. The class got an array with a maximum of 4 link to other class and it can be circular(this is why I have a checked_link boolean).It does the recursion until there is no more link(return false) to check or until it find the middle link(return true).
edit?for an example, this
in pos 0 got link with 1
in pos 0 got link with 6
in pos 1 got link with 0
[code]....
middlepoint would be pos 15 the code above can prove that every position can be linked with the middlepoint so initial arg would be
everythingLinked(random pos, false)
and in this case it would be always true
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Jun 26, 2009
I'm trying to put together a quick example for another thread about treeviews, and I'm getting a problem when I have a recursive routine, getting the message.
Quote:
There is already an open DataReader associated with this Command which must be closed first.
I'm a tad confused as I am explicitly creating a new command every time through the loop, so I'm not sure (unless its something ADO is doing behind the scenes) how the datareaders higher up the tree are interfering.
Here's my code :
Private Sub SetupChildren(ByVal ParentID As Integer, ByRef ParentNode As TreeNode)
Dim MyCommand As New SqlCommand("SELECT * FROM Groups WHERE ParentGroup=@ParentGroup", m_myConnection)
[Code]...
Obviously I could close the data reader down before calling the next level of recursion but it would prevent the code continuing the loop at the current level when it had finished processing children.
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Apr 14, 2010
I have two forms. A main form and then another form that you can change settings in. Now when I click on the menu item to get to the settings form I get this error. "An error occurred creating the form. See Exception.InnerException for details. The error is: The form referred to itself during construction from a default instance, which led to infinite recursion. Within the Form's constructor refer to the form using 'Me.'"I've tried these codes.
frmSettings.Show()
Application.Run(frmSettings)
those didn't work so i tried these
dim settings as new form = frmSettings
settings.show()
dim settings as form
[code]....
and those didn't work. I'm using visual studio 2010 Pro.
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Mar 14, 2010
I have a program that has a large set of classes in it. A certain incident (I won't call it an event, yet, as that has a specific meaning that will cause trouble later) needs to a relatively small subset of these classes a question. The subset of classes will need to respond to the question, but for it to be able to do so, the classes may first need to ask a similar question of the same subset, which may prompt yet a further question, though this recursion will never go more than three or four levels down. Since only a small subset of these classes will participate in the questions, while the majority will never participate, and since all of these classes are virtually identical, and I can know at design time whether any given class is part of the subset or not, an event is appropriate. The main class can raise an event, and those classes in the subset can handle the event, while those classes that are not in the subset won't handle the event. Furthermore, any of these classes can raise the event again with different parameters, as needed. Thus far, an event appears to be ideal.
The problem is this: As a result of the event, each class will need to add one or more strings to one of two lists. Event handlers can't return anything, so I can't be using the return values from functions to populate these lists.
Two options appear possible:
1) Include the two lists in the event arguments.
2) Have the two lists be accessible to all classes, and don't pass anything around.
The second part of the problem is that the event is effectively a question being asked of each class, and no action can be taken until each class has responded. If I simply raise an event and let each class respond, can I be certain that all classes that should respond have? An alternative solution would be to have each class expose a method, and call these methods for each class in turn. By doing this, I could get return values, but I would have to call the methods for ALL the classes, not just the subset that actually cares (the classes are all different types, but they all implement a common interface, and are added to a List (of ) that interface, so I can iterate through them all without much difficulty). So, the event seems more efficient, but adding a function to the common interface for the classes is the approach most certain of being a solution.
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Jun 26, 2011
i am developing a program in visual basic 2010, it involves a non- linear iteration of one of the two variables with a step of .00 and a match at the .000 (3rd) decimal placethere cannot be an exact match between the 2 variable's values but i need the iteration to stop at the nearest possible value.
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Nov 15, 2011
I just can't seem to understand when i am suppose to put Accept outside the LOOP and when i'm suppose to Accept inside the LOOP at the beginning.
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Jan 23, 2012
Is the warning I am receiving about using the iteration variable in this line a concern.
Dim reportdataforpage = (From reportvar In reportdata Where reportvar.reportpage = pagenum)
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Aug 25, 2009
how to assign one value to whole array without iteration through it? for example a i have pArray (5000,5000) =1 where all members off array = 1.
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Jun 13, 2012
I have noticed that when iterating DataGridViewColumns, the speed is greatly reduced if the columns are visible.
For Each col As DataGridViewColumn In cData.DataGridView.Columns
col.Visible = visible
Next
If visible is set to false (and all columns are all currently visible), iterating 264 columns takes around 0.35s, however, if visible is set to true (and all columns are currently invisible), the same process takes around 30s.Does anyone know what would be causing the extra time?Could it something internal to the DataGridView Control?
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Jun 18, 2009
Does a For-Each loop in VB have an iteration count, or would I have to do that myself?
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Nov 10, 2009
I've got a for loop. In my loop , I've got a condition , and if that condtion is not met, I need to move on to the next iteration.
So if I have :
For Each txt As Control In tbcell.Controls
if TypeOf (txt) Is CheckBox Then
[code]....
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Sep 23, 2011
Background: I am working on an ASP.net project that basically fills out a form from user input. The generated form (for reasons which I have no control over) must be a JPEG or TIFF. So the user fills out the web form, which takes all of the input values and meges them into a blank image (jpeg) of the form. Using System.Drawing, it merges all of the text onto the form at designated Points. The points are defined as variables which are modified at runtime to compensate for the resolution of the image (in case it get modified/re-generated at a different dpi). All of this is working fine.
Problem: Currently I have a Sub that determines the dpi of the master image, then adjusts the Points accordingly. However, there are ~50 variables that have to be adjusted. So currently I have the Sub go thru each point variable and manually adjust the X & Y values. I have been working on a Sub that will iterate thru all of the Point variables and do adjustment. Here's a functional sample of what I have working:Imports System.Drawing
Partial Class test Inherits System.Web.UI.Page
[Code]...
This works...sort of. It allows me to grab each variable and modify it, but only in the instance. The original variable in the class is unchanged. Which means that when the program gets to the point where it's drawing text to the image, the points are unmodified. my basic question is: Is it possible to modify the original variable using this sort of process? If not, is the best way to use these modified values to declare the new class instance at a global level, then have the Sub that draws the text use the instance versions of the variables?
I realize that I could define all of the points in an array which would be easy to loop thru and update, but I've named each point variable something meaningful to correspond to the related text to be drawn.
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Jul 20, 2011
I have been given the task of converting an old program from Vb 5 that needs to be able to run in VB2010. I have read a few forums on the subject but whatever I try doesn't work. The .bas files convert over fine and the code from the forms comes over, but the forms do not appear. Instead there is a bunch of gibberish. How can I convert this? I tried going to version 6, which the forms worked in, and then to 2010, but I couldn't get the vbp file to show up or the forms.
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Jul 6, 2010
I created a VB.NET winforms project using Visual Studio 2003, including reports done with CRystal Reports. I need to upgrade the system to the latest VB.NET using Visual Studio 2010. What kind of problems can I expect? How difficult will it be to convert the reports to Business Objects (which I believe is now th default in V Studio).
It's not a huge system about 6-8 screens and a similar number of reports using an Access 2000 Database. Most of the screens were coded directly in VB and not done with the automated processes at the time.
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Sep 21, 2010
lI think I almost have this done but I get and error "'Public ReadOnly Property Right As Integer' has no parameters and its return type cannot be indexed."here is the line causing the error:
If UCase(StrKey) = ".DEFAULT" Or UCase(Right(StrKey, 8)) = "_CLASSES" Then
whole code
Const HKEY_USERS = &H80000003
Const ForAppending = 8
Const OverwriteExisting = True
[code]....
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Jan 9, 2011
I came about these two functions (ReadHEX and WriteHEX) that, obviously, read a hex offset or write a hex offset of a file. However, these functions were written in VB6. The main thing I'm not understanding is how to open a file (in a filestream I presume) and then to either read or write a certain offset from the file. I'd also need to convert the string I'm writing to hex before I actually right it, but I've got that under control. Here's the current functions as they were written:
[Code]...
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Apr 15, 2012
I'm flummoxed I'm using VB.Net, Linq, and a DataContext. My DataContext contains a table 'transactions'.
I first declare an IQueryable(Of transaction) and assign it to nothing. I build a predicate in a foreach loop and use a transactions.Where(predicate) to assign the IQueryable a value. If I do an IQueryable.ToList(), I get a number of items in the collection.
However, on the next iteration of the loop, the IQueryable.ToList() gives me 0 items.This is driving me crazy. I tried to use the LINQ to SQL Debug Visualizer with VS2010, (I recompiled the 2008 version with the new reference) but no dice - I can't see the SQl generated or what's inside the IQueryable.
[Code]...
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Oct 13, 2010
I have List (of class). having 1800 of count and each object has 90 properties. When I terate earch with 90 properties taking more and more time. How to resolve this
Dim cellIntStyle As HSSFCellStyle = hssfworkbook.CreateCellStyle
cellIntStyle.DataFormat = HSSFDataFormat.GetBuiltinFormat("#")
Dim cellDateStyle As HSSFCellStyle = hssfworkbook.CreateCellStyle
[Code]....
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Feb 16, 2012
[URL]..Module Module1
[Code]...
It says the result will always be 5 namely the final value of i. How come?
They don't put the iteration variable in the "closure"?
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