I am attempting to make a random number generator in VB 16 in Visual Studio, but every time I run this I keep getting 71, I've tried making it public, sharing it and several other things, but it won't work. I am trying to make a program that has the user guess a randomly generated number, and continue guessing until they get it, but for some reason the exact same number is chosen each time. It won't work properly specifically in window app forms. How do I get a random number each time?
Public Shared Randomize()
Dim value As Integer = CInt(Int((100 * Rnd()) + 1))
Public Sub EnterBtn_Click(sender As Object, e As EventArgs) Handles EnterBtn.Click
Dim entervalue As String = EnterTxt.Text
Dim chances As Integer
Select Case entervalue
Case > value
ResTxt.Text = "Too big"
chances += 1
Case < value
ResTxt.Text = "Too small"
chances += 1
Case = value
ResTxt.Text = "Well done, you got it in " & chances & " tries"
End Select
End Sub
You were close! Here's a working example modifying your original logic:
Private random As Random = New Random()
Private value As Integer
Private chances As Integer
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
value = random.Next(1, 100)
chances = 0
End Sub
Private Sub EnterBtn_Click(sender As Object, e As EventArgs) Handles EnterBtn.Click
Select Case EnterTxt.Text
Case > value
chances += 1
ResTxt.Text = "Too big"
Case < value
chances += 1
ResTxt.Text = "Too small"
Case = value
chances += 1
ResTxt.Text = "Well done, you got it in " & chances & " tries"
'and reset for next attempt
value = random.Next(1, 100)
chances = 0
End Select
End Sub
Since your code is not correct it is hard to pinpoint the problem. It is also not clear what the code is supposed to do.
Try this
Private Shared PRNG As New Random ' add this
value = PRNG.Next(1, 101)'this will set value to a random number between 1 and 100 inclusive
Here's some skeleton code for you:
Dim rnd As New Random()
For i as Integer = 0 to 10
Console.WriteLine("{0,15:N0}", rnd.Next())
Next
Notice the rnd.Next() thing. Hope it helps.
Related
First of all, I would like you to know that I am really rookie on this platform and in vb.net language. I have a question, I wanted to ask you, since I couldn't make any progress in about 3 hours. I think it's very simple for someone who knows.
If the number entered from the textbox is odd, multiply by 3 and add 1, if it is double, this process will be divided by 2, and this process should continue until the number is "1". I try to write the code of the program that finds how many steps this process takes (number of processes), the maximum value of the number during the process and the number that the number always reaches 1 in pairs with VB.NET.
Is there anyone who can help? I want you to know that I was really struggling, trying to learn, but not enough
As I said, I scribbled something, but I am not even on the right track.
enter image description here
enter code here
Dim number1 As Double
Dim tislem As Double
Dim result As Double
Dim çislem As Double
Dim i As Double
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
number1 = TextBox1.Text
çislem = number1 / 2
tislem = number1 * 3 + 1
If number1 Mod (2) = 1 Then
result = tislem
MessageBox.Show("sayı tektir" + result.ToString())
For i = 1 To result = 0
result = number1 / 2
Next i
MessageBox.Show("sayı tektir" + result.ToString())
Else MessageBox.Show("sayı çifttir")
End If
End Sub
I'm not sure if I understood exactly what you're trying to do (neither of us have english as a first language it seems). I'm still trying, but make sure that you understand what I'm doing or I may lead you off target.
It seems to me that the worst problem here is using a For loop instead of a While loop. You could also do without some of these variables. Here's some code to give you a hand:
' I suggest that you add these two lines at the very top of your code
' It'll force you to type your variables, which is a great way to avoid all kind of mistakes
Option Explicit On
Option Strict On
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
' Here I'm protecting you against errors caused if the user enters a non-numeric
' Your teached probably didn't ask for this but it's good to know nonetheless
If Not String.IsNullOrWhiteSpace(TextBox1.Text) AndAlso IsNumeric(TextBox1.Text) Then
' Converting text to double (it was done implicitely in your code, but it's better to understand what's happening to better control it)
Dim myNumber As Double = CDbl(TextBox1.Text) ' CDbl as in 'Convert DouBLe'
Dim maxNumber as Double = myNumber
' If the number is odd, we multiply by 3 and add 1
If myNumber Mod 2 = 1 Then
myNumber = (myNumber * 3) + 1
If myNumber > maxNumber Then maxNumber = myNumber
End If
' Let's count how many divisions before there's only 1 left
Dim i As Integer = 0
While (myNumber > 1)
myNumber = myNumber / 2
i += 1
End While
MessageBox.Show("It took " & i.ToString & " divisions until my number was reduced to 1. The max number was " & maxNumber.ToString & ".")
Else
' This will appear if you try to use non-numeric, like letters
MessageBox.Show("Use only numbers.")
End If
End Sub
Have fun!
Try something like this,
Dim number1 As Double
Dim maxNumber As Double = 0
Dim steps as Double = 0
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
number1 = TextBox1.Text
MessageBox.Show($"Sayı {If( (number1 Mod 2) = 1, "tektir", "çifttir") }")
While number1 > 1
number1 = If((number1 Mod 2) = 1, number1 * 3 + 1, number1 * 2)
maxNumber = Math.Max(number1, maxNumber)
steps += 1
End While
MessageBox.Show($"Steps: {steps}{Environment.NewLine}Max number reached: {maxNumber}")
End Sub
You should write a proper loop in order to repeat this process until you reach 1. Moreover, it is better for you that if you get used to use & symbol instead of + symbol to concat strings.
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
I'm trying to loop this array 100 times (gets a number from 0-99,999). I've tried it several different ways with no luck. I've got it set up so you click a button and it generates the array. The user will then enter a number and hit the other button to check how many times that number shows up in the group of a 100 numbers. Any thoughts how to fix it? I'm stuck.
Dim i As Integer
Dim rnd As New Random()
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnEnter.Click
Dim num As Integer
If Int32.TryParse(txtEnter.Text, num) AndAlso num >= 0 AndAlso num < 10 Then
lblNumber.Text = i.ToString()
Dim counts = From c In i.ToString()
Group By c Into Group
Select DigitGroup = New With {.Count = Group.Count(), .Digit = c, .Group = Group}
Order By DigitGroup.Count Descending, DigitGroup.Digit
Dim numCount = counts.FirstOrDefault(Function(grp) grp.Digit.ToString() = num.ToString())
If numCount IsNot Nothing Then
Dim numMessage = String.Format("There are {0} number {1}'s found.", numCount.Count, num)
MessageBox.Show(numMessage)
Else
MessageBox.Show("Your number does not contain a " & num)
End If
Else
MessageBox.Show("Please enter a number between 0 and 9.")
End If
End Sub
Private Sub btnGetNumber_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnGetNumber.Click
btnEnter.Enabled = True
i = 0
Do Until i > 100
Dim randomInt = rnd.Next(0, 100000)
i = i + 1
i = rnd.Next(0, 100000)
Loop
End Sub
End Class
First of all, it is common to use For Loops when you know the number of loops.
Secondly, you forgot to increment i in the until loop
Finally, you don't need to redeclare rnd in every loop. Something like that sounds better to me :
Dim rnd As New Random()
For i = 1 To 100
Dim randomInt = rnd.Next( 0 , 100000 )
Next
Move the New Random() out of that loop. Make it global and create the instance just one time.
(The Random generator starts using a seed obtained from the current time. Declaring a Random variable inside a loop result in the same seed used again and again. This gives back the same number defeating the randomness of the function) It is like: http://xkcd.com/221/
See another explanation here
Of course, if you don't increment the variable i used to control the loop, you will loop forever
Dim i As Integer
Dim rnd As New Random()
.....
i = 0
Do Until i > 100
Dim randomInt = rnd.Next(0, 100000)
i = i + 1
Loop
Said that, now I can't get what are you trying to do here. There is no array to check and you do not use the value obtained from the Random generator, simply, your i variable exits with value 101.
Now I am just guessing what are your intentions, but perhaps you want just this?
i = rnd.Next(0, 100000)
This will give to the variable i a random number and your subsequent code checks how many, of the required digit, are present in i
I see that you are not adding the variable "i" to increment:
i = 1
Do Until i > 100
Dim rnd As New Random()
Dim randomInt = rnd.Next(0, 100000)
i+=1 'Increment value of i by 1, same as i = i + 1
Loop
The variable of "i" will always be 1 if not incremented. Check that and let me know if that solves the problem!
I have exhausted all of my options and am very desperate for help since I cannot figure out where the bug in my code is, or if there is something I don't understand.
I'm trying to create a "methinks it is a weasel!" mimmick from Richard Dawkins' late 80s documentary about evolution. The goal is to progress through a genetic algorithm until the algorithm guesses the correct answer through mutation and fitness tournaments.
Now, here's the problem:
Private Function fitnessTourney(ByVal editGuess() As Guess, ByVal popIndex As Integer, ByVal tourneySize As Integer, ByVal popNum As Integer)
Dim randInt(tourneySize - 1) As Integer
Dim loopCount1 As Integer = 0
Dim fitnessWinner As New Guess
fitnessWinner.setFitness(-50)
...
And, this loop is where I am experiencing the critical error
...
For i = 0 To tourneySize - 1
Randomize()
randInt(i) = Int(Rnd() * popNum)
While editGuess(randInt(i)).Used = True
If loopCount1 > tourneySize Then
loopCount1 = 0
For i2 = 0 To popNum - 1
editGuess(i2).setUsed(False)
Next
i = -1
Continue For
End If
loopCount1 += 1
randInt(i) = Int(Rnd() * popNum)
End While
editGuess(randInt(i)).determineFitness(correctPhrase)
editGuess(randInt(i)).setUsed(True)
Next
For i = 0 To popNum - 1
editGuess(i).setUsed(False)
Next
What this loop is trying to do is pick out four random instances of the editGuess array of objects. This loop tries to prevent one from being used multiple times, as the population is competing to one of the 10 members (highest fitness of the 4 chosen candidates is supposed to win).
The critical error is that I mysteriously get an endless loop where any instances of editGuess(randInt(i)).Used will always evaluate to true. I have tried to fix this by resetting all instances to False if it loops too many times.
The stumper is that I'll have all instances evaluate to False in the debugger. Then, when I reach "editGuess(randInt(i)).setUsed(True)" (the exact same thing as "editGuess(randInt(i)).Used = True"), it sets this value for EVERY member of the array.
Is there anyone who can see what is happening? I am so close to completing this!
Here's the Guess class:
Public Class Guess
Dim Fitness As Integer
Dim strLength As Integer
Dim strArray(30) As String
Dim guessStr As String
Dim Used As Boolean
Public Sub New()
Fitness = 0
guessStr = ""
strLength = 0
Used = 0
End Sub
Public Sub determineFitness(ByVal correctPhrase As String)
Dim lowerVal
If guessStr.Length <= correctPhrase.Length Then
lowerVal = guessStr.Length
Else
lowerVal = correctPhrase.Length
End If
strArray = guessStr.Split("")
Fitness = 0 - Math.Abs(correctPhrase.Length - guessStr.Length)
For i = 0 To lowerVal - 1
If correctPhrase(i) = guessStr(i) Then
Fitness = Fitness + 1
End If
Next
End Sub
Public Sub Mutate(ByVal mutatepercentage As Decimal, ByVal goodLetters As String)
If mutatepercentage > 100 Then
mutatepercentage = 100
End If
If mutatepercentage < 0 Then
mutatepercentage = 0
End If
mutatepercentage = mutatepercentage / 100
If Rnd() < mutatepercentage Then
strLength = Int(Rnd() * 25) + 5
If strLength < guessStr.Length Then
guessStr = guessStr.Remove(strLength - 1)
End If
End If
For i = 0 To strLength - 1
If Rnd() < mutatepercentage Then
If i < guessStr.Length Then
guessStr = guessStr.Remove(i, 1).Insert(i, goodLetters(Int(Rnd() * goodLetters.Length)))
Else
guessStr = guessStr & goodLetters(Int(Rnd() * goodLetters.Length))
End If
End If
Next
End Sub
Public Sub setFitness(ByVal num As Integer)
Fitness = num
End Sub
Public Sub setStrLength(ByVal num As Integer)
strLength = num
End Sub
Public Sub initializeText()
End Sub
Public Sub setUsed(ByVal bVal As Boolean)
Used = bVal
End Sub
End Class
And, finally, here's where and how the function is called
Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
population1(counter) = fitnessTourney(population1, counter, 4, 10)
population2(counter) = fitnessTourney(population2, counter, 4, 10)
population1(counter).Mutate(2, goodLetters)
population2(counter).Mutate(20, goodLetters)
Label1.Text = population1(counter).guessStr
Label2.Text = population2(counter).guessStr
counter += 1
If counter > 9 Then
counter = 0
End If
End Sub
End Class
EDIT 1:
Thank you guys for your comments.
Here is the custom constructor I use to the form. This is used to populate the population arrays that are passed to the fitnessTourney function with editGuess.
Public Sub New()
InitializeComponent()
Randomize()
For i = 0 To 9
population1(i) = New Guess
population2(i) = New Guess
Next
counter = 0
correctPhrase = "Methinks it is a weasel!"
goodLetters = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ !##$%^&*()_+-=?></.,;\|`'~"
goodLettersArr = goodLetters.Split("")
For i = 0 To 9
population1(i).setStrLength(Int(Rnd() * 25) + 5)
population2(i).setStrLength(Int(Rnd() * 25) + 5)
For i2 = 0 To population1(i).strLength
population1(i).guessStr = population1(i).guessStr & goodLetters(Int(Rnd() * goodLetters.Length))
Next
For i2 = 0 To population2(i).strLength
population2(i).guessStr = population2(i).guessStr & goodLetters(Int(Rnd() * goodLetters.Length))
Next
Label1.Text = population1(i).guessStr
Label2.Text = population2(i).guessStr
Next
population1(0).guessStr = correctPhrase
population1(0).determineFitness(correctPhrase)
End Sub
I haven't studied all of your code thoroughly, but one big problem is that you are calling Randomize from within the loop. Every time you call Randomize, it re-seeds the random numbers with the current time. Therefore, if you call it multiple times before the clock changes, you will keep getting the first "random" number in the sequence using that time which will always evaluate to the same number. When generating "random" numbers, you want to re-seed your random number generator as few times as possible. Preferably, you'd only seed it once when the application starts.
As a side note, you shouldn't be using the old VB6 style Randomize and Rnd methods. Those are only provided in VB.NET for backwards compatibility. You should instead be using the Random class. It's easier to use too. With the Random class, you don't even need to call a randomize-like method, since it automatically seeds itself at the point in time when you instantiate the object. So, in the case of the Random class, the thing to be careful is to make sure that you only instantiate the object once before entering any loop where you might be using it. If you create a new Random object inside a loop, it will similarly keep generating the same numbers.