Is it possible to write an infinite for loop in VB.NET?
If so, what is the syntax?
Do
Something
Loop
For i as Integer = 0 To 1 Step 0
If that's not hacky enough, can also write:
For i As Integer = 0 To 2
i -= 1
Next
or
while (true)
end while
ok, proper For answer:
Dim InfiniteLoop as Boolean = true;
For i = 1 to 45687894
If i = 45687893 And InfiniteLoop = true Then i = 1
End For
Aside from all the many answers given to make a loop run forever, this may just be the first that actually uses the value of Positive Infinity to cap the loop. Just to be safe though, I included an extra option to exit after a given number of seconds so it can measure the speed of your loop.
Sub RunInfinateForLoop(maxSeconds As Integer)
' Attempts to run a For loop to infinity but also exits if maxSeconds seconds have elapsed.
Dim t As Date = Now
Dim exitTime As Date = t.AddSeconds(maxSeconds)
Dim dCounter As Double
Dim strMessage As String
For dCounter = 1 To Double.PositiveInfinity
If Now >= exitTime Then Exit For
Next
strMessage = "Loop ended after " & dCounter.ToString & " loops in " & maxSeconds & " seconds." & vbCrLf &
"Average speed is " & CStr(dCounter / maxSeconds) & " loops per second."
MsgBox(strMessage, MsgBoxStyle.OkOnly, "Infinity Timer")
End Sub
What I do is add a timer then I change the interval to 1 and then I make it enabled then If I want it to constantly check something through the loop I just double click the timer for the timer_tick event then I type what I want. I usually use this for updating the settings if I want it to save every thing.
Related
I have a program that creates 100 000 objects of class Client, puts them into array and then goes through that array 100 times, each time assigning each Client a different random number through Rnd() function:
Main sub:
Sub start()
Dim i As Long
Dim j As Long
Dim clientsColl() As Client
ReDim clientsColl(1 To 100000) As Client
For j = 1 To 100000
Set clientsColl(j) = New Client
clientsColl(j).setClientName = "Client_" & j
Application.StatusBar = "Getting client " & j
DoEvents
Next
Dim tempCount As Long
Dim clientCopy As Variant
For i = 1 To 100
tempCount = 0
For Each clientCopy In clientsColl
tempCount = tempCount + 1
clientCopy.generateRandom
'Application.StatusBar = "Calculating " & i & ": " & tempCount & "/" & 100000 '(1)
'DoEvents
Next
Application.StatusBar = "Calculating " & i
DoEvents
Next
MsgBox ("done")
End Sub
Client class:
Option Explicit
Dim clientName As String
Dim randomNumber As Double
Public Sub generateRandom()
randomNumber = Rnd()
End Sub
Public Property Get getClientName()
getClientName = clientName
End Property
Public Property Let setClientName(value As String)
clientName = value
End Property
The problem is, the execution time depends on whether or not line (1) is commented out. If it's executed, the statusbar gets renewed, but the execution time is very slow. If it's not executed, the program gets done really fast.
Why does this happen?
VBA is fast enough as long as you stay within. Whenever you turn to Excel, it may get much slower because Excel makes thousands of operations every time it gets control. You may consider turning off a few more services of Excel like I do in my applications:
Application.Calculation = xlCalculationManual
Application.ScreenUpdating = False
Application.DisplayStatusBar = False
Application.EnableEvents = False
ActiveSheet.DisplayPageBreaks = False
... and as far as I know DoEvents is the best way to make Excel update the status bar when you turn off automatic updates.
Another timesaving workaround can be to display only every 100th or 1000th message from within the inner loop.
when doing a progressbar or statusbar, you need to use it wisely.
Basically the progress info needs to be refreshed only every 0.1 seconds or so.
Knowing your max number of loops , and the time it takes, you might want to update the info only every (in your case) , let's say, 100 iterations of the loop.
This is done like this: if j mod 100=0 then application.statusbar="..." : doevents
Usually i even go further by using doevents less than my progressbar (second if j mod).
I am trying to create a bowling program that will display the scores given in a multi-line text box. I've manage to get the program giving an output, but when it runs it skips asking for new inputs and just gives 5 0s on seperate lines and nothing else. I'm completely lost, any help is very much appreciated
EDIT: Sorry should have changed errors to reflect the programs changes, it looks like this now. It gives 0's instead of using the value I gave it, but it does ask for each input now.
For gameNumber As Integer = 1 To 5 Step 1
lblEnterScore.Text = "Enter Score for game #" & gameNumber
Dim Testint As Integer ' define an Integer for testing
Try
Testint = CInt(txtScoreInput.Text) ' try to convert whatever they entered to Int
Catch
MessageBox.Show("Entry is not an Integer") ' If you are here then the CInt failed for some reason, send a message
txtScoreInput.SelectAll()
txtScoreInput.Focus()
Exit Sub
End Try
If txtScoreInput.Text.Contains(".") Then
MsgBox("Bowling Score must be a whole number.")
txtScoreInput.SelectAll()
txtScoreInput.Focus()
Exit Sub
End If
If txtScoreInput.Text > MAXIMUM_SCORE Or txtScoreInput.Text < MINIMUM_SCORE Then
MsgBox("Bowling Score must be between 1 and 300.")
txtScoreInput.SelectAll()
txtScoreInput.Focus()
Exit Sub
End If
scoreInput(gameNumber) = CInt(txtScoreInput.Text)
' and store it in the array
' and increment the gamecounter for the next time through the loop
Next
'btnEnterScore.Enabled = False
' place the good score into the multi-line textbox
txtScoreOutputs.Text = gameScore & vbCrLf & txtScoreOutputs.Text
End Sub
If it was me, here's what I would do... Just a suggestion; I also cut out over half of your code and stopped it from throwing exceptions as well... You can put this in a click event or where ever you need it as well. You can modify this as well to take as many as you want from user input as well not just limit them from entering score's. Your user also has the option to get out of that loop when they choose to do so as well, not keeping them inside the loop...
Private ScoreLists As New List(Of Integer) 'Hold your inputted values
Private Const MAXIMUM_SCORE As Integer = 300 'Max score
Private Const MINIMUM_SCORE As Integer = 1 'Min score
Private blnStop As Boolean = False
Try
For gameNumber As Integer = 1 To 5
Dim intScore As Integer = 0
Do Until (intScore >= MINIMUM_SCORE And intScore <= MAXIMUM_SCORE) OrElse blnStop
If Not Integer.TryParse(InputBox("Please enter a score for game # " & gameNumber.ToString), intScore) Then
If MsgBox("Bowling Score must be a whole number. Stop getting scores?.", MsgBoxStyle.YesNo) = MsgBoxResult.Yes Then
blnStop = True
Exit For
End If
End If
Loop
ScoreLists.Add(intScore)
Next
'Display the results...
For i As Integer = 0 To ScoreLists.Count - 1
txtScoreOutputs.Text &= ScoreLists.Item(i.ToString)
Next
ScoreLists.Clear()
Catch ex As Exception
End Try
Construct your logic like this (pseudo):
Loop
{
AskUserForInput()
ProcessUserInput()
}
The loop part will control how many scores the user is prompted to enter. The AskUserForInput() function will prompt the user to type in a new score, and the ProcessUserInput() function will get the value and store it in an array or print it to the screen, etc.
Your current logic is not waiting for any new user input before trying to add to the scores. You are also getting zeros because you're setting the txtScoreOutputs with gameScore, which doesn't look like it's been set to the user's input.
Imgur Album with screens of worksheets: http://imgur.com/a/6rFWF
Long story short, I am writing an Excel VBA utility that will assign two types of security shifts (called coverages and weekend duties) to security staff members. Basically, I have a worksheet with all of the staff members and their various availability information in it (the top image in the imgur album) and a worksheet with all of the coverage dates in it (the bottom image in the imgur album). Note that I don't have an image of the weekend duty dates as it looks similar to the coverage dates (but with the Friday and Saturday shifts).
The utility basically assigns a random staff member to each date, checking to make sure it doesn't violate any of their availability requirements. Unfortunately, I realize that I am creating a large chance for an infinite loop to occur. In my own testing, there has only been 1 attempt out of around 15-16 that did not enter an infinite loop near the end. So I'm looking for your help to account for this so the utility doesn't eat itself.
Here is the "pseudo-code" for the procedure in question.
'Loop for Column A in the Coverage Slips sheet (image 2 in imgur album)
Do Until (CoverageRowNumber = LastCoverageSlipRow + 1)
Get a Random Staff Member by RNG
If staff member still needs more shifts (see Requirements columns) Then
If staff member does not have an "X" under the day of the week Then
If staff member does not have a matching date conflict Then
Assign the coverage
Increase CoverageRowNumber
End If
End If
End If
Loop
'Loop for Column B in the coverage slips sheet (image 2 in imgur album)
Do Until...
Same as the loop above
Loop
Edit: Disregard that I have the dates in two columns for now. I'll be fixing that once I solve the problem of this post...it's an easy fix and will cut the code almost in half.
The problem is that as the utility gets near the end of the list of dates, it often runs into the scenario where the only staff members left cannot sit that specific shift (whether because of day of the week or specific date). In the event that it runs into this scenario, I can see a couple of acceptable options (though I don't know how I'd go about programming them):
Undo all of the work that the utility did and start over until it can get lucky and find a solution that works. This would save me some time doing manual placements for the last few shifts but might take a very long time. Additionally, I'd have to store all of the original values and then paste them back into the spreadsheet anytime it starts over.
Simply stop assigning shifts and just exit the procedure. I will be able to manually place the last few shifts by moving a few people around. I sure is a lot less work than manually assigning 200 shifts by hand like I've been doing it the past few years.
Do you guys have any thoughts that could be of help here? I'm not even sure how I could have the procedure check to see if there are any available options or not, but either way there's got to be a way to detect (and deter) this infinite loop before it crashes the program.
Sorry for the novel, and thanks in advance for any help!
Edit: In an effort to provide a little more clarity, I figured I'd copy and paste the actual code below:
'------------------------------------------------------------'
'Create ws variables for each worksheet
Dim wsConflicts As Worksheet
Dim wsCoverageSlips As Worksheet
Dim wsWDSlips As Worksheet
Dim wsCoverageOutput As Worksheet
Dim wsWDOutput As Worksheet
'------------------------------------------------------------'
Public Function SetSheets()
'Assign the worksheets to the ws variables
Set wsConflicts = Worksheets("Conflicts")
Set wsCoverageSlips = Worksheets("Coverage Slips")
Set wsWDSlips = Worksheets("WD Slips")
Set wsCoverageOutput = Worksheets("Coverage Output")
Set wsWDOutput = Worksheets("WD Output")
'Display a message (debugging)
'MsgBox "The sheets have been assigned successfully"
End Function
'------------------------------------------------------------'
Public Function ColumnLetter(ColumnNumber As Integer) As String
Dim n As Long
Dim c As Byte
Dim s As String
n = ColumnNumber
Do
c = ((n - 1) Mod 26)
s = Chr(c + 65) & s
n = (n - c) \ 26
Loop While n > 0
ColumnLetter = s
End Function
'------------------------------------------------------------'
Sub AssignCoverages()
'Fill the ws variables
Call SetSheets
'Set the first and last row numbers
Dim FirstStaffMemberRow As Integer
FirstStaffMemberRow = 3
Dim LastStaffMemberRow As Integer
LastStaffMemberRow = wsConflicts.UsedRange.Rows.Count
'Count the number of required coverages and weekend duties
Dim RequiredCoverages As Integer
Dim RequiredWDs As Integer
For i = FirstStaffMemberRow To LastStaffMemberRow
RequiredCoverages = RequiredCoverages + wsConflicts.Range("B" & i).Value
RequiredWDs = RequiredWDs + wsConflicts.Range("C" & i).Value
Next i
'Display a message (debugging)
MsgBox "You currently have " & RequiredCoverages & " required coverages and " & RequiredWDs & " required weekend duties."
'Count the number of coverage slips and weekend duty slips
Dim FirstCoverageSlipRow As Integer
FirstCoverageSlipRow = 1
Dim LastCoverageSlipRow As Integer
LastCoverageSlipRow = wsCoverageSlips.UsedRange.Rows.Count
Dim NumCoverageSlips As Integer
NumCoverageSlips = (LastCoverageSlipRow - FirstCoverageSlipRow + 1)
Dim FirstWDSlipRow As Integer
FirstWDSlipRow = 1
Dim LastWDSlipRow As Integer
LastWDSlipRow = wsWDSlips.UsedRange.Rows.Count
Dim NumWDSlips As Integer
NumWDSlips = (LastWDSlipRow - FirstWDSlipRow + 1)
'Check to make sure there are enough required shifts for slips
If RequiredCoverages <> NumCoverageSlips Then
MsgBox "The number of shifts you require (Columns B & C on Conflicts sheet) does not match the number of slips you've entered. You have " & RequiredCoverages & " required coverages and " & NumCoverageSlips & " coverage slips. You have " & RequiredWDs & " required weekend duties and " & NumWDSlips & " weekend duty slips. Please correct this error and retry."
Exit Sub
Else
'Debugging
'MsgBox "The number of shifts you require (Columns B & C on Conflicts sheet) matches the number of slips you've entered. You have " & RequiredCoverages & " required coverages and " & NumCoverageSlips & " coverage slips. You have " & RequiredWDs & " required weekend duties and " & NumWDSlips & " weekend duty slips."
End If
'Massive loop to assign coverages to random staff members
Dim NumRemainingCoverages As Integer
NumRemainingCoverages = NumCoverageSlips
Dim SlipRowNumber As Integer
SlipRowNumber = FirstCoverageSlipRow
'Loop for Column A
Do Until (SlipRowNumber = LastCoverageSlipRow + 1)
'Get a random staff member row
StaffMemberRow = GetRandomStaffMemberRow(FirstStaffMemberRow, LastStaffMemberRow)
'Check to make sure the staff member has remaining required coverages
If wsConflicts.Range("B" & StaffMemberRow).Value > 0 Then
'Check to make sure the staff member can sit the day of the week
Dim CurrentDate As Date
CurrentDate = wsCoverageSlips.Range("A" & SlipRowNumber).Value
Dim CurrentDay As Integer
CurrentDay = Weekday(CurrentDate)
Dim CurrentDayColumn As String
If CurrentDay = 1 Then CurrentDayColumn = "D"
If CurrentDay = 2 Then CurrentDayColumn = "E"
If CurrentDay = 3 Then CurrentDayColumn = "F"
If CurrentDay = 4 Then CurrentDayColumn = "G"
If CurrentDay = 5 Then CurrentDayColumn = "H"
If CurrentDay = 6 Then CurrentDayColumn = "I"
If CurrentDay = 7 Then CurrentDayColumn = "J"
If wsConflicts.Range(CurrentDayColumn & StaffMemberRow).Value = "" Then
'Check to make sure the staff member does not have a date conflict
Dim ColumnNumber As Integer
Dim ColumnLetterText As String
Dim CoverageDateConflicts As Integer
CoverageDateConflicts = 0
For ColumnNumber = 11 To 20
ColumnLetterText = ColumnLetter(ColumnNumber)
Dim CoverageSlipDate As Date
If IsDate(wsConflicts.Range(ColumnLetterText & StaffMemberRow).Value) = True Then
CoverageSlipDate = wsConflicts.Range(ColumnLetterText & StaffMemberRow).Value
Else
CoverageSlipDate = DateValue("01/01/1900")
End If
If CurrentDate = CoverageSlipDate Then
CoverageDateConflicts = CoverageDateConflicts + 1
End If
Next ColumnNumber
If CoverageDateConflicts = 0 Then
'Assign the coverage
Dim BlankCoverageOutputRow As Integer
BlankCoverageOutputRow = wsCoverageOutput.UsedRange.Rows.Count + 1
wsCoverageOutput.Range("A" & BlankCoverageOutputRow).Value = wsConflicts.Range("A" & StaffMemberRow).Value
wsCoverageOutput.Range("B" & BlankCoverageOutputRow).Value = CurrentDate
'Reduce the staff member's required coverages by 1
Dim CurrentRequirements As Integer
CurrentRequirements = wsConflicts.Range("B" & StaffMemberRow).Value
wsConflicts.Range("B" & StaffMemberRow).Value = CurrentRequirements - 1
'Reduce the number of remaning coverages by 1
NumRemainingCoverages = NumRemainingCoverages - 1
'Increase the slip row number by 1
SlipRowNumber = SlipRowNumber + 1
'Message box for debugging
'MsgBox "Coverage Date (" & CurrentDate & ") assigned to " & wsConflicts.Range("A" & StaffMemberRow).Value & "."
End If 'End date check
End If 'End day check
End If 'End requirements check
Loop 'End loop for column A
End Sub
'------------------------------------------------------------'
Public Function GetRandomStaffMemberRow(FirstStaffMemberRow As Integer, LastStaffMemberRow As Integer)
'Pick a random number between the first staff member row and the last
Call Randomize
GetRandomStaffMemberRow = Int((LastStaffMemberRow - FirstStaffMemberRow + 1) * Rnd + FirstStaffMemberRow)
End Function
The question is too open for a detailed answer, so I try with some guidelines. I hope it helps.
I would use a class Solution with the following members:
Solution.ReadInputFromSheet() reads the table from the sheet into the class members
Solution.GenerateRandom() creates a new random solution. Try to find a balance between smart (add some logic to avoid totally random solutions) and speed (don't get stuck, exit after trying 10 or 50 random numbers that don't work), but speed is more important
Solution.Quality() As Double calculates the quality of the solution. For example a solution that is not valid returns 0, if Joe has 10 consecutive shifts returns 20, if the shifts are better distributed returns 100.
Solution.WriteOnSheet() write the data from the class members into the sheet.
Solution.Clone() As Solution() creates a new Solution instance with the same data
Make a cycle that creates a solution, checks if its quality is better than the best quality solution found so far, if it is better keep it, otherwise go and calculate another solution.
Set BestS = New Solution
BestS.ReadInputFromSheet
BestS.GenerateRandom()
Set S = New Solution
S.ReadInputFromSheet
For I = 1 To 10000
S.GenerateRandom()
If S.Quality() > BestS.Quality() Then Set BestS = S.Clone()
Next I
BestS.WriteOnSheet
Instead of 10000 you can use Timer to run it for a finite number of seconds, or make a button to interrupt it when you come back from lunch break.
A faster solution generator function is better than risking of getting stuck with one difficult (or impossible) solution.
For a smarter solution generator function I need more details on the rules.
So I went ahead and developed my own solution to this problem--it's not perfect and it's probably not the best way to handle the scenario. But it works, and it solved my problem in a matter of minutes instead of hours learning other methods.
Basically, I created two new "counter" variables. The first is FailedAttempts. Every time the procedure tries a random staff member but runs into a conflict, it increments FailedAttempts by 1. Every time the random staff member is a successful match (no conflicts), it resets FailedAttempts to 0. If at any time FailedAttempts = 100, it immediately exits the loop and starts over. In other words, if it tries 100 random staff members in a row without finding a match, I assume it's not going to find a match and just cut my losses.
The second variable, Assignments, is incremented by 1 every time that the procedure makes a successful assignment. When this number equals the number of shifts that the procedure is supposed to assign, it immediately exits the loop.
To do this, I had to use a couple of forbidden 'GoTo' commands (I wasn't sure how else to exit the loop. You can exit a For loop with Exit For but I believe this is invalid for Do While loops. I ended up only needing two GoTo's, one for exiting the loop and one to go back to the beginning of the procedure. I also made sure that the cells in the worksheet that change during the procedure are reset to their original state before it retries the assignment procedure.
I'll save everyone the trouble of reading through the extended version of the code, but in 'pseudo-code' form it looks like this:
Retry: 'Label for GoTo command
Do Until (CoverageRowNumber = LastCoverageSlipRow + 1)
Get a Random Staff Member by RNG
If staff member still needs more shifts (see Requirements columns) Then
If staff member does not have an "X" under the day of the week Then
If staff member does not have a matching date conflict Then
'Assign the coverage
'Increase CoverageRowNumber
Assignments = Assignments + 1
Else
FailedAttempts = FailedAttempts + 1
End If
Else
FailedAttempts = FailedAttempts + 1
End If
Else
FailedAttempts = FailedAttempts + 1
End If
If FailedAttempts > 100 Then
GoTo ExitLoop
End If
Loop
ExitLoop: 'Label for GoTo command
If Assignments <> NumCoverageSlips Then
GoTo Retry
End If
'Do rest of procedure
Again, there may be (and certainly is) a more elegant and "correct" way of accomplishing the task at hand. This method worked for me with the given environment. Thanks to those who provided solutions--even though I ended up going a different direction they provided great food for thought and helped me learn a bunch of new methods (especially the class idea from #stenci).
Thanks all.
I am working on a project which allows kids to send a message to Santa. Unfortunately, if they enter a string instead of an integer in the AGE field, the program crashes and returns Conversion from string "[exampleString]" to type 'Double' is not valid.
Is there any way to check if they have entered an integer or not? This is the code.
If childAge > 0 And childAge < 150 Then
fmSecA2 = "Wow! You are already " & childAge & " years old? You're growing to be a big " & childGender & " now! "
Else
fmSecA2 = "Erm, I couldn't really understand your age. Are you making this up? Ho ho ho!"
End If
Thanks,
Kai :)
A very simple trick is to try parse the string as an Integer. If it succeeds, it is an integer (surprise surprise).
Dim childAgeAsInt As Integer
If Integer.TryParse(childAge, childAgeAsInt) Then
' childAge successfully parsed as Integer
Else
' childAge is not an Integer
End If
Complementing Styxxy's response, if you dont need a result just replace it by vbNull:
If Integer.TryParse(childAge, vbNull) Then
You could perform the following two tests to be reasonably certain that the input you're getting is an integer:
If IsNumeric(childAge) AndAlso (InStr(1, childAge, ".") <> 0) Then
fmSecA2 = "Wow! You are already " & childAge & " years old? You're growing to be a big " & childGender & " now! "
If childAge < 0 OrElse childAge > 150 Then
fmSecA2 = "I don't believe it's possible to be" & childAge & " years old..."
End If
Else
fmSecA2 = "Erm, I couldn't really understand your age. Are you making this up? Ho ho ho!"
The InStr function returns zero if it doesn't find the string that is being looked for, and so when combining that test with IsNumeric, you also rule out the possibility that some floating point data type was entered.
IsNumeric is built into VB, and will return a true/false
If IsNumeric(childAge) AndAlso (childAge > 0 And childAge < 150) Then
fmSecA2 = "Wow! You are already " & childAge & " years old? You're growing to be a big " & childGender & " now! "
Else
fmSecA2 = "Erm, I couldn't really understand your age. Are you making this up? Ho ho ho!"
End If
You can use this.
Sub checkInt()
If IsNumeric(Range("A1")) And Not IsEmpty(Range("A1")) Then
If Round(Range("A1"), 0) / 1 = Range("A1") Then
MsgBox "Integer: " & Range("A1")
Else
MsgBox "Not Integer: " & Range("A1")
End If
Else
MsgBox "Not numeric or empty"
End If
End Sub
Working from Styxxy's answer, if you parse as a byte rather than an integer, then it also checks negative ages and maximum age of 255 all in one go.
Dim childAgeAsByte As Byte
If Byte.TryParse(childAge, childAgeAsByte) Then
' childAge successfully parsed as Byte
Else
' childAge is not a Byte
End If
Kristian
Dim Input
Input = TextBox1.Text
If Input > 0 Then
............................
............................
Else
TextBox2.Text = "Please only enter positive integers"
End If
Try
If TextBox1.Text > 0 Then
Label1.Text = "Integer"
End If
Catch ex As Exception
Label1.Text = "String"
End Try
With this you can put anything in TextBox1, if you put text then you get Label1 is string and if you put number then you get it's integer
In .Net you may use GetType() to determine the data type of a variable.
Dim n1 As Integer = 12
Dim n2 As Integer = 82
Dim n3 As Long = 12
Console.WriteLine("n1 and n2 are the same type: {0}",
Object.ReferenceEquals(n1.GetType(), n2.GetType()))
Console.WriteLine("n1 and n3 are the same type: {0}",
Object.ReferenceEquals(n1.GetType(), n3.GetType()))
' The example displays the following output:
' n1 and n2 are the same type: True
' n1 and n3 are the same type: False
Based on the above sample you can write a code snippet:
If childAge.GetType() = "Integer" then '-- also use childAge.GetType().Name = "Int32"
' do something
End if
Reference MSDN
I'm using visual studios 2008, VB9 and I am trying to write an app that basically performs calculations on a set of data input by a user. During the calculations, I want to display the data at each step, and have it retained in the display area on the GUI (not overwritten by the next data being displayed).
For example:
UserInput = 1
Do
UserInput += 1
OutputLabel.Text = "UserInput " & UserInput
Loop Until UserInput = 5
and the output would look like
UserInput 1
UserInput 2
UserInput 3
UserInput 4
UserInput 5
I tried this, and other loop structures and can't seem to get things right. The actual app is a bit more sophisticated, but the example serves well for logical purposes.
Any tips are welcome, thanks!
This is the simple version:
Dim delimiter as String = ""
For UserInput As Integer = 1 To 5
OutputLabel.Text &= String.Format("{0}UserInput {1}", delimiter, UserInput)
delimiter = " "
Next
However, there are two problems with it and others like it (including every other answer given so far):
It creates a lot of extra strings
Since it's in a loop the label won't be able to process any paint events to update itself until you finish all of your processing.
So you may as well just do this:
Dim sb As New StringBuilder()
Dim delimiter As String = ""
For UserInput As Integer = 1 To 5
sb.AppendFormat("{0}UserInput {1}", delimiter, UserInput)
delimiter = " "
Next
OutputLabel.Text = sb.ToString()
And if you really want to have fun you can just do something like this (no loop required!):
OutputLabel.Text = Enumerable.Range(1, 5).Aggregate(Of String)("", Function(s, i) s & String.Format("UserInput {0} ", i))
You need to concatenate the value in OutputLabel.Text.
OutputLabel.Text &= "UserInput " & UserInput
You might also want to reset it before the loop: OutputLabel.Text = ""
If you need an iterated index you can try something like the following
For I As Integer = 1 To 5
If I > 1 Then OutputLabel.Text &= " "
OutputLabel.Text &= "UserInput " & I.ToString()
End For
If you have user inputs in a collection, you might better be served by using ForEach loop.
Do you need to do it in a GUI? If it is simply processing and putting out rows like that, maybe you should consider a console application, in which case it becomes REALLY easy, in simply calling
Console.WriteLine("my string")
All of these ways actually work really well but the one that fit my situation the best was this:
Do
Dim OutputString as String
Application.DoEvents() 'to make things paint actively
UserInput += 1
OutputString = String.Format("{0}", UserInput)
ListBox.Items.Add(OutputString)
Loop Until UserInput = 5
I changed things to a listbox but tried this same method with textboxes and labels, with some tweaks, they all worked very well. Thanks for all your help!
I'd use a more appropriate control, like richtextbox
Dim UserInput As Integer = 0
Const userDone As Integer = 5
RichTextBox1.Clear()
Do
RichTextBox1.AppendText(String.Format("User input {0:n0} ", UserInput))
RichTextBox1.AppendText(Environment.NewLine)
RichTextBox1.Refresh() 'the data at each step
UserInput += 1
Loop Until UserInput = userDone