I am currently working on a homework assignment for Visual basic. The homework is to display the square value of only the odd numbers 1-9. I have to use a For Next to do so as specified by the assignment. I do not want the answer but a point to the right direction. Here is my code currently it only displays the square value of 9 but will not display the square value of the other odd numbers. I have done a couple tutorials but I can not figure out why it ill not continue the loop.
Public Class MainForm
Private Sub exitButton_Click(sender As Object, e As EventArgs) Handles exitButton.Click
Me.Close()
End Sub
Private Sub displayButton_Click(sender As Object, e As EventArgs) Handles displayButton.Click
'Start/end values and retainer for the values
Dim startVal As Integer
Dim endVal As Integer
Dim squareVal As Integer
startVal = 1
endVal = 9
'For loop to separate the odd and even numbers to square the odd numbers.
For _val As Integer = startVal To endVal Step 1
If _val Mod 2 <> 0 Then
squareVal = _val * _val
squaresLabel.Text = squareVal.ToString() & ControlChars.NewLine
_val += 1
Else
squaresLabel.Text = _val.ToString() & ControlChars.NewLine
_val += 1
End If
Next _val
End Sub
End Class
You are overwriting the text stored in squaresLabel each pass through the loop. Look at the assignment statement:
squaresLabel.Text = squareVal.ToString() & ControlChars.NewLine
I think you are just repeating the calculation not actually output each value. So I suggest you define an array and store them inside of it. Also do trouble shooting for each value. Hope it helps.
Related
I am trying to get the combinations of all possible unrepeated character sets from the user input.
As I am just beginning to learn the programming, it is obvious that I don't properly understand how those nested loops work.
Here is my code:
Public Class Form1
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
ListBox1.Items.Clear()
Dim c1 As String = TextBox1.Text
Dim i, j As Integer
Dim str As String()
Dim k As Integer = 0
For i = 0 To c1.Length - 1
For j = 0 To i
ListBox1.Items.Add(c1(i) & c1(j))
Next
Next
End Sub
End Class
As you can see in the picture attached, I cannot get the rest. How can I get the character pairs I put in the red box on notepad?
Can someone help me, please.enter image description here
You had the right idea. However, expand your logic so that for every letter of the outer loop you spin through every letter again. And if you don't want repeated letter pairs, add an If statement:
For i = 0 To c1.Length - 1
For j = 0 To c1.Length - 1
If i <> j Then ListBox1.Items.Add(c1(i) & c1(j))
Next
Next
I would like to make a simple program that does the following
Takes a text input of a string and the number of times it needs to be looped by the program user and produces that loop to output that string the number of times stated. My loop isn't doing that. (New to visual basic loops)
Kindly correct advise where i have gone wrong below:
Public Class Form1
Private Sub cmdLoop_Click(sender As Object, e As EventArgs) Handles cmdLoop.Click
Dim newput As String
Dim numberr As Integer
Dim counter As Integer
newput = txtStatement.Text
numberr = TxtRepeatNum.Text
For counter = 1 To numberr
lbloutput.Text = newput & vbCrLf
Next
End Sub
Your loop is writing numberr times the same string into the text box, with every iteration it overwrites the previous content. Change it to
lbloutput.Text = ""
For counter = 1 To numberr
lbloutput.Text = lbloutput.Text & newput & vbCrLf
Next
in my programming class I have to create a program which allows the user in order to enter a sentence, with the buttons "Encode" and "Decode" as options. So, for "Encode", you have to translate the sentence into Asc numbers (already did this). However, I'm currently stuck on the "Decode" section, for you have to use a For loop and an array to separate the Asc numbers by spaces, then translate them into characters one by one. Here's what I have so far:
Public Class Form1
Dim Message As String
Dim NewMessage As String
Dim Part As String
Dim Part2 As Integer
Dim Letter As String
Dim Length As String
Dim ints() As Integer
Dim intlength As Integer
Private Sub btn_Enter_Click(sender As Object, e As EventArgs) Handles btn_Enter.Click
Message = txt_Message.Text
Length = Message.Length() - 1
If rbn_Encode.Checked = True Then
For Num As Integer = 0 To Length
Letter = Message(Num)
Me.lbl_Code.Text = lbl_Code.Text & Asc(Letter) & " "
Next
End If
If rbn_Decode.Checked = True Then
For Num As Integer = 0 To intlength Step 1
If Message(Num) <> " " Then
Part = Part & Message(Num)
Else
NewMessage = NewMessage & ChrW(Part) & " "
End If
Next
Me.lbl_Code.Text = NewMessage
End If
End Sub
Private Sub ExitToolStripMenuItem_Click(sender As Object, e As EventArgs) Handles ExitToolStripMenuItem.Click
Application.Exit()
End Sub
End Class
I've been stuck on this for about 2 week, and I'm still clueless. Thank you for your help and have a wonderful day.
This might seem to veer off the topic of the question, but it all meanders towards a better answer.
OK there are a few issues with your code. Firstly, make sure that "Option Strict" is on - have a look here. This will force you to convert types properly and reduce the potential for problems. Bearing the above in mind,
Dim Length As String
should be
Dim Length As Integer
on to the next bit
Each procedure should have a single responsibility. Your btn_Enter.Click event handler includes code for encoding text and decoding numbers. These should be separated out into their own procedures. In a relatively short bit of code like yours, it's not too much of a problem, but even here, it makes things a little fuzzier. Have a look at the code below. There are more issues, but we'll look at them in a moment. The code below is a bit clearer and more maintainable.
Private Sub btn_Enter_Click(sender As Object, e As EventArgs) Handles btn_Enter.Click
Message = txt_Message.Text
Length = Message.Length() - 1
If rbn_Encode.Checked = True Then
EncodeTextToAscii()
End If
If rbn_Decode.Checked = True Then
DecodeToText()
End If
End Sub
Private Sub DecodeToText()
For Num As Integer = 0 To intlength Step 1
If Message(Num) <> " " Then
Part = Part & Message(Num)
Else
NewMessage = NewMessage & ChrW(Part) & " "
End If
Next
Me.lbl_Code.Text = NewMessage
End Sub
Private Sub EncodeTextToAscii()
For Num As Integer = 0 To Length
Letter = Message(Num)
Me.lbl_Code.Text = lbl_Code.Text & Asc(Letter) & " "
Next
End Sub
Next.
In your code to encode the string as ASCII, you store the resulting data directly in the label lbl_Code's text property. The user interface should never be used as the primary store for data. It's bad practice and potentially allows the user to change data accidentally - in textboxes for example. In the case of a label, it's not to important, but it's far better to get into the good habits.
To store your encoded ASCII numbers, you can use the array ints, but as your code stands, the declaration of ints is just that. There is no space in the array to store data. So, in the Encode procedure, you need to resize ints to the same as the number of characters in the string.
So now we have ..
Private Sub EncodeTextToAscii()
ReDim ints(Length)
For Num As Integer = 0 To Length
Letter = Message(Num)
ints(Num) = Asc(Letter)
Next
End Sub
Finally onto the meat of your question. The Decode procedure can now be written as this ..
Private Sub DecodeToText()
NewMessage = ""
For Each asciiNumber As Integer In ints
NewMessage = NewMessage & ChrW(asciiNumber) & " "
Next
Me.lbl_Code.Text = NewMessage
End Sub
Instead of mucking around getting the length of a loop and getting the ascii number in each element of an array, you can simplyfy it using a For Each statement. You dont need to know the length of the array. It just loops over the whole length. Much easier.
As an excercise, try applying the For Each idea to the Encode procedure. :-)
This question already has answers here:
Generating Even Random Numbers
(2 answers)
Closed 8 years ago.
trying to make a random number generator using visual basic for a school project. The user would enter in 2 different values in textbox1 and textbox 2, press a button and a random number would be generated between these 2 digits (this random number would be displayed in textbox3). This was too basic for the project, so i decided to add in 2 checkboxs which, when checked would make the generated number either even or odd.
Really need some help with an algorithm that limits the random number to be even or odd. Any help is greatly appreciated! :) (checkbox1 is for making it even, checkbox2 for odd)
Dim answer As Integer
Dim result As Integer
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
TextBox3.Clear()
TextBox3.Text = answer
If CheckBox1.Checked = False And CheckBox2.Checked = False Then
answer = CInt(Int((TextBox2.Text * Rnd() + TextBox1.Text)))
End If
^ the above code also seems to generate random numbers in a specific order, always starting from 0, any help with this would be greatly appreciated :)
If CheckBox1.Checked = True Then
Do Until result = 0
result = CDec(TextBox1.Text / 2) - CInt(TextBox1.Text / 2)
Loop
If result = 0 Then
answer = CInt(Int((TextBox2.Text * Rnd() + TextBox1.Text)))
End If
End If
End Sub
This is what I'd do to solve this problem:
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) 'Handles Button1.Click
'Parse the two numbers
Dim minValue = Integer.Parse(TextBox1.Text)
Dim maxValue = Integer.Parse(TextBox2.Text)
'Create a list of all possible valid numbers
Dim values = Enumerable.Range(minValue, maxValue - minValue).ToArray()
'Keep only the even numbers if selected
If CheckBox1.Checked Then
values = values.Where(Function (v) v Mod 2 = 0).ToArray()
End If
'Keep only the odd numbers if selected
If CheckBox2.Checked Then
values = values.Where(Function (v) v Mod 2 = 1).ToArray()
End If
'Check there are numbers
If values.Length = 0 Then
TextBox3.Text = "There no available numbers to choose."
Else
'`rnd` here is `System.Random` as I didn't know what `Rnd()` was.
TextBox3.Text = values(rnd.Next(0, values.Length)).ToString()
End If
End Sub
You could use a function to generate either an even or odd number depending on which checkbox is checked, the functions would use mod to determine whether the generated number id even/odd. If it is not what you require, then it would try again until the generated number matches. For example:
Private Sub btnGenerate_Click(sender As System.Object, e As System.EventArgs) Handles btnGenerate.Click
If chkOdd.Checked Then
GenerateOdd()
ElseIf chkEven.Checked Then
GenerateEven()
End If
End Sub
Private Function GenerateOdd()
Dim r = CInt(Math.Ceiling(Rnd() * 100))
If ((r Mod 2) = 0) Then
'r is even, generate another number and try again
GenerateOdd()
Else
'r is odd we have a match
yourTextBox.Text = r
Return r
End If
Return Nothing
End Function
Private Function GenerateEven()
Dim r = CInt(Math.Ceiling(Rnd() * 100))
If ((r Mod 2) = 0) Then
'r is even, we have a match
yourTextBox.Text = r
Return r
Else
'r is odd, generate another number and try again
GenerateEven()
End If
Return Nothing
End Function
I haven't tried this but you get the point!
*Edit - the (Rnd() * 100)) is a random number between 1 and 100
Recently when creating a program for my client as part of my computing project in visual basic .net I've came across a problem, which looks like following; In order to receive additional marks for my program I must take an advantage of either Binary Search or Insertion Sort subroutine declared recursively, so far the only place I can use it on is my View form which displays all reports generated by program but the problem with this is since I'm using MS Access to store my data all of the data is downloaded and placed in listview in load part of form. So the only way I can use it is by running it on listview which is a major problem for me due to the fact that I'm not very experienced in vb.
For binary search I have tried downloading all of the items in specified by user column into an array but that's the bit I was struggling on the most because I'm unable to download all items from only one column into an array. Also instead of searching every single column user specifies in my form in which column item is located (For example "19/02/2013" In Column "Date"), In my opinion if I manage to download every single entry in specified column into an array it should allow me to run binary search later on therefore completing the algorithm. Here's what I've got so far.
Sub BinarySearch(ByVal Key As String, ByVal lowindex As String, ByVal highindex As String, ByVal temp() As String)
Dim midpoint As Integer
If lowindex > highindex Then
MsgBox("Search Failed")
Else
midpoint = (highindex + lowindex) / 2
If temp(midpoint) = Key Then
MsgBox("found at location " & midpoint)
ElseIf Key < temp(midpoint) Then
Call BinarySearch(Key, lowindex, midpoint, temp)
ElseIf Key > temp(midpoint) Then
Call BinarySearch(Key, midpoint, highindex, temp)
End If
End If
End Sub
Private Sub btnSearch_Click(sender As System.Object, e As System.EventArgs) Handles btnSearch.Click
Dim Key As String = txtSearch.Text
Dim TargetColumn As String = Me.lstOutput.Columns(cmbColumns.Text).Index
Dim lowindex As Integer = 0
Dim highindex As Integer = lstOutput.Items.Count - 1
'Somehow all of the items in Target column must be placed in temp array
Dim temp(Me.lstOutput.Items.Count - 1) As String
' BinarySearch(Key, lowindex, highindex, temp)
End Sub
For Insertion sort i don't even have a clue how to start, and the thing is that I have to use my own subroutine instead of calling system libraries which will do it for me.
Code which I have to use looks like following:
Private Sub InsertionSort()
Dim First As Integer = 1
Dim Last As Integer = Me.lstOutput.
Dim CurrentPtr, CurrentValue, Ptr As Integer
For CurrentPtr = First + 1 To Last
CurrentValue = A(CurrentPtr)
Ptr = CurrentPtr - 1
While A(Ptr) > CurrentValue And Ptr > 0
A(Ptr + 1) = A(Ptr)
Ptr -= 1
End While
A(Ptr + 1) = CurrentValue
Next
Timer1.Enabled = False
lblTime.Text = tick.ToString
End Sub
Any ideas on how to implement this code will be very appreciated, and please keep in my mind that I'm not very experienced in this language
Perhaps this might give you a place to begin. If you already have a ListView with "stuff" in it you could add a button to the form with the following code to copy the Text property for each item into an array:
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim myArray(Me.ListView1.Items.Count - 1) As String
Dim i As Integer
' load array
For i = 0 To Me.ListView1.Items.Count - 1
myArray(i) = Me.ListView1.Items(i).Text
Next
' show the results
Dim s As String = ""
For i = 0 To UBound(myArray)
s &= String.Format("myArray({0}): {1}", i, myArray(i)) & vbCrLf
Next
MsgBox(s, MsgBoxStyle.Information, "myArray Contents")
' now go ahead and manipulate the array as needed
' ...
End Sub