I am writing code for a form that is supposed to determine whether a value inputted by the user is valid as a check digit. They input a 13 digit number and it should determine whether or not the last value is valid as a check digit. I have written in the code for the check digit algorithm but I'm having trouble with comparing the value that the algorithm found with what the user input. I have tried using the substring method to compare the 13th number given by the user with the check digit that the algorithm determined but I am having issues with the syntax of everything.
This is the code I have been working on:
Private Sub btnValidate_Click(sender As Object, e As EventArgs) Handles btnValidate.Click
Dim intDigit As Integer
Dim intTotalOdd As Integer
Dim intTotalEven As Integer
Dim intGrandTotal As Integer
Dim intRemainder As Integer
Dim intCheckDigit As Integer
If txtNumber.Text.Length = 13 Then
For intOdd As Integer = 1 To 11 Step 2
intTotalOdd += (intDigit * 3)
Next intOdd
For intEven As Integer = 0 To 10 Step 2
intTotalEven += intDigit
Next intEven
intGrandTotal = intTotalOdd + intTotalEven
intRemainder = intGrandTotal Mod 10
If intRemainder <> 0 Then
intCheckDigit = 10 - intRemainder
End If
If txtNumber.Text.Substring(12, 13) = intCheckDigit Then
lblStatus = "Valid"
Else
lblStatus = "Not Valid"
End If
End If
End Sub
I think the way I'm doing it should work but I don't have very much to reference on how I would go about making the syntax work. Will the way that I'm trying to do it work or do I need to go about it in a different way?
Related
I am trying to create a simple counter that increases when the button is clicked.
What I would like is when the counter is clicked it displays "01", "02" etc.
I can create it already with "1", "2", but I would like to have a leading zero.
I have searched and found I can do this by converting the label to a string, but I cant seem to get the value to count?
If I change "count.text = counter" to "count.text = cot" it will display "01", but wont count. I'm guessing this is due to the fact its only displaying what is currently in the string but not increasing the value?
If I could get any guidance that would be great!
Many thanks!
Dim counter As Integer = 1
Dim cot As String = String.Format("{0:00}", counter)
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
counter = cot + 1
count.Text = counter
End Sub
PadLeft is the key.
Dim number as Integer = 12
Console.WriteLine(number.ToString().PadLeft(2, "0")). ' prints 12
number = 2
Console.WriteLine(number.ToString().PadLeft(2, "0")). ' prints 02
The problem is, that you don't update your formatted number properly. It's only initialized a single time.
To increment the counter, use counter += 1 or counter = counter + 1 first. This will add 1 to the current value of the integer variable. Then modify the text of your Label by calling that formatting code again: count.Text = String.Format("{0:00}", counter).
This should get you started...
it converts the string into an integer. increments the number, converts it back into a string and then checks for a leading 0, if not found it adds it.
I will let you convert it into your button click for practise, as it should help you have a good understanding of the conversion between types :)
Sub string_counter()
Dim string_counter As String
string_counter = "00"
For x = 0 To 10
Debug.Print string_counter
string_counter = Int(string_counter) + 1
string_counter = Str(string_counter)
If Left(Trim(string_counter), 1) <> "0" Then
string_counter = "0" + Trim(string_counter)
End If
Next x
End Sub
I'm on visual basic and I'm reading through some piece of code my teacher wrote, he had this chunck of code:
Private Sub btnDividing_Click(sender As Object, e As EventArgs) Handles btnDividing.Click
Dim number As Integer = InputBox("Divide number by 2:")
Dim result As Integer = 0
Do While (number <> 0)
result += 1
number = number - 2
Loop
MsgBox("The result is: " & result, MsgBoxStyle.Exclamation)
End Sub
So my teacher typed the result += 1 and number = number -2 I didn't really understand that part so i tried simplifying it by changing it to:
Dim number As Integer = InputBox("Divide number by 2:")
Dim result As Integer = 0
Do While (number <> 0)
result = number / 2
Loop
MsgBox("The result is: " & result, MsgBoxStyle.Exclamation)
End Sub
but it keeps freezing after I click "OK"
Any suggestions?
It freezes because you made it an infinite loop:
Do While (number <> 0)
result = number / 2
Loop
The loop checks the value of number, but your modified code in the loop never modifies the value of number. So if the condition is true the first time it's checked, it will always be true. The original code modified the value:
Do While (number <> 0)
result += 1
number = number - 2
Loop
Since number is decremented by 2 with each iteration of the loop, it will eventually (assuming it's even) be equal to 0, making the loop condition false and the loop will end.
Basically, a loop needs to in some way modify the values being checked in the condition (or have some other control statement to exit the loop) or the loop will infinitely run.
"Write a program which reads in a start and an end value. The program then stores all the even numbers between these two values (inclusive) in an array. The user is then asked to select a number (n), the program should output the nth even number"
Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
number1 = InputBox("Enter first number")
number2 = InputBox("enter second number")
Any guidance on this would be much appreciated, I'm completely lost.
Ok, the edit is making more sense to me now. You were on the right track getting the first three inputs. Then we neeed to do 2 things to our inputs:
1) Get the even numbers within the range the user has given us
2) Return the nth term if it exists
I would approach the problem like this:
'Get our inputs
Dim number1 As Integer = CInt(InputBox("Enter first number"))
Dim number2 As Integer = CInt(InputBox("Enter second number"))
Dim nthTerm As Integer = CInt(InputBox("Enter Nth Term"))
Dim evenNumbers As New List(Of Integer)
'Now, we want to get a list of all the even numbers within n1 to n2 range
For i As Integer = number1 To number2
'if the number divided by 2 has a remainder of 0, then it's an even number
If i Mod 2 = 0 Then evenNumbers.Add(i)
Next
'Now that we have all the even #s, try to return the nth one as long as it exists
Try
'We substract 1 from the nthTerm entered by used to account for list's 0-based index
MsgBox(evenNumbers(nthTerm - 1).ToString)
Catch ex As Exception
MsgBox("Nth Term out of bounds")
End Try
I am creating a program to generate numbers between a list of values.
Problem I am having is if the first number stats with a smaller value than the second value it will create an error, such as 1000 and 32 will say it doesnt work, or 532 and 64
I do not understand why or how to fix it
Private Sub Generate_Click(sender As System.Object,
e As System.EventArgs) Handles Generate.Click
'Displays to enter correct information if lower is <=
If Upper.Text <= Lower.Text Or Lower.Text >= Upper.Text Then
List.Items.Clear()
List.Items.Add("Please enter correct info Upper # higher value than Lower #")
Else
'If Upper range is higher than lower range then display numbers until total value is displayed
List.Items.Clear()
Number.Text = ""
Dim i As Integer = Lower.Text
Do While i <= Upper.Text 'Loop generates the numbers between values specified
List.Items.Add(i)
i += 1
Loop
'Select a random value from the list generated
Dim myRandom As New Random
Dim b As Integer = List.Items.Count
Dim chosenItem As System.Object = List.Items.Item(myRandom.Next(b))
Number.Text = chosenItem.ToString
End If
End Sub
Basically you have to compare numeric value you are comparing string so it is happening.
And 'or' condition is not required in if statement so omit it.
please replace you code as follows.
if System.Convert.ToInt32(Upper.Text) <= System.Convert.ToInt32(Lower.Text) Then
List.Items.Clear()
List.Items.Add("Please enter correct info Upper # higher value than Lower #")
Else
List.Items.Clear()
Number.Text = ""
Dim i As Integer = Lower.Text
Do While i <= System.Convert.ToInt32(Upper.Text) 'Loop generates the numbers between values specified
List.Items.Add(i)
i += 1
Loop
'Select a random value from the list generated
Dim myRandom As New Random
Dim b As Integer = List.Items.Count
Dim chosenItem As System.Object = List.Items.Item(myRandom.Next(b))
Number.Text = chosenItem.ToString
End If
With the If clause, you are doing a string comparison on numerical values. You need to cast them to integer values. And you are doing the same comparison twice which is unnecessary. Also there is a simpler way of generating random numbers between two integers.
I would encourage you to code with the "Option Strict On" declaration at the top of the page. The compiler will alert you when you attempt to make implicit conversions of which there are several in your code.
Dim iMinimum As Integer = Integer.Parse(Lower.Text)
Dim iMaximum As Integer = Integer.Parse(Upper.Text)
If iMaximum <= iMinimum Then
Number.Text = "Please enter correct info Upper # higher value than Lower #"
Else
Dim randomObject As Random = New Random
Number.Text = randomObject.Next(iMinimum, iMaximum).ToString
End If
This code generates a stack overflow. I'm aware it is caused by the procedure calling itself.
What can I do to avoid the stack overflow? Recalling the sub procedure and generating a new random number is the easiest thing to do, however it generates the overflow. The randomly generated number picks a random inventory item, then the if statement matches that number (random inventory item) with the quantity of that item from the deck inventory to make sure it isn't less than 1. If the inventory of that item is 0, the else plays and restarts the procedure, generating a new random number and doing the process all over again. In another procedure I have a function that if the deck's inventory becomes completely empty, then the discard pile replenishes the deck, making the discard pile empty, so there should never be a case where all randomly generated numbers can be associated item with a inventory of 0.
I wonder if I could somehow force the random number generator
Number = (DeckGroup(Rnd.Next(0, DeckGroup.Count)).ID)
not to generate numbers to inventory items DeckGroup(Number).QuantityInteger that are zero. By doing so I wouldn't even need to recall the function.
The random number is generated by a different branch in the same structure group.
Private Sub PlayElse()
Dim CardCheckBoxArray() As CheckBox = {CardCheckBox1, CardCheckBox2, CardCheckBox3, CardCheckBox4, CardCheckBox5}
'Reset Number Generator
Number = (DeckGroup(Rnd.Next(0, DeckGroup.Count)).ID)
Dim PlayerQuantitySubtractionInteger As Integer
For PlayerQuantitySubtractionInteger = ChecksDynamicA To ChecksDynamicB
If CardCheckBoxArray(TextBoxInteger).Checked = True And DeckGroup(Number).QuantityInteger > 0 Then
DeckGroup(Number).QuantityInteger -= 1
'Select the Player depending value of T
Select Case T
Case 0
Player1HandGroup(Number).QuantityInteger += 1
Case 1
Player1HandGroup(Number).QuantityInteger2 += 1
Case 2
Player1HandGroup(Number).QuantityInteger3 += 1
Case 3
Player1HandGroup(Number).QuantityInteger4 += 1
Case 4
Player1HandGroup(Number).QuantityInteger5 += 1
End Select
CardTypeArray(PlayerQuantitySubtractionInteger) = Player1HandGroup(Number).CardType
CardCheckBoxArray(TextBoxInteger).Text = Player1HandGroup(Number).CardNameString
NumberArray(PlayerQuantitySubtractionInteger) = Number
Else
If CardCheckBoxArray(TextBoxInteger).Checked = True And DeckGroup(Number).QuantityInteger < 0 Then
Call PlayElse()
End If
End If
Next PlayerQuantitySubtractionInteger
End Sub
You could use LINQ to weed out all the objects you never want to get first and then use the collection returned by the linq instead of your original collection.
Something like:
Private Sub PlayElse()
Dim CardCheckBoxArray() As CheckBox = {CardCheckBox1, CardCheckBox2, CardCheckBox3, CardCheckBox4, CardCheckBox5}
'Reset Number Generator
Dim temp As IEnumerable(Of LunchMoneyGame.LunchMoneyMainForm.Group) = From r In DeckGroup Where r.QuantityInteger > 0 Select r
If temp IsNot Nothing AndAlso temp.Any Then
Number = (temp(Rnd.Next(0, temp.Count)).ID)
' ** Edit **: This will ensure that you only got 1 object back from the LINQ which can tell you whether or not you have bad data. You *can* exclude this check but its good practice to include it.
Dim obj As LunchMoneyGame.LunchMoneyMainForm.Group = Nothing
Dim t = From r In temp Where r.ID = Number Select r
If t IsNot Nothing AndAlso t.Count = 1 Then
obj = t(0)
End If
If obj IsNot Nothing Then
Dim PlayerQuantitySubtractionInteger As Integer
For PlayerQuantitySubtractionInteger = ChecksDynamicA To ChecksDynamicB
' ** Edit **
obj.QuantityInteger -= 1
'Select the Player depending value of T
Select Case T
Case 0
Player1HandGroup(Number).QuantityInteger += 1
Case 1
Player1HandGroup(Number).QuantityInteger2 += 1
Case 2
Player1HandGroup(Number).QuantityInteger3 += 1
Case 3
Player1HandGroup(Number).QuantityInteger4 += 1
Case 4
Player1HandGroup(Number).QuantityInteger5 += 1
End Select
CardTypeArray(PlayerQuantitySubtractionInteger) = Player1HandGroup(Number).CardType
CardCheckBoxArray(TextBoxInteger).Text = Player1HandGroup(Number).CardNameString
NumberArray(PlayerQuantitySubtractionInteger) = Number
Next PlayerQuantitySubtractionInteger
End If
End If
End Sub
Pass through the list and determine only those that are valid. Then randomly pull from that set. Here is a simple version of it. You could use LINQ as well, but this should be clear enough:
Dim validDeckGroupsIndexes As New List(Of Integer)
For ndx As Integer = 0 to DeckGroup.Count - 1
If DeckGroup(ndx).QuantityInteger > 0 Then
validDeckGroupsIndexes .Add(ndx)
End If
Next ndx
Then use this:
Dim deckGroupNdx As Integer = Rnd.Next(0, validDeckGroupsIndexes.Count)
Number = DeckGroup(deckGroupNdx).ID