One of my assignments in vb.net is to make a program that takes in 15 inputted "test scores", returns the average, and then returns the corresponding letter grade. I am trying to make this as short as possible, and I remembered a code format that I can use when I am coding in Python (simple example with only three scores):
counter = 0
number = 0
test1,test2,test3 = 0,0,0
for i in [test1,test2,test3]:
print("Enter a test score")
i = int(input())
counter += i
number += 1
average = counter/number
Is there such a code format in VB.NET?
Yes.
Here is a simple sample code which asks user to input number of items and then items one by one. At the end it calculates average of numbers.
Console.WriteLine("Enter number of Items")
Dim numberOfItems As Integer
If Integer.TryParse(Console.ReadLine(), numberOfItems) Then
Dim items As New List(Of Decimal)()
For i As Integer = 1 To numberOfItems
Console.WriteLine("Enter number {0}", i)
Dim num As Decimal
If Decimal.TryParse(Console.ReadLine(), num) Then
items.Add(num)
End If
Next
Console.WriteLine("Average is " + items.Average())
Console.ReadLine()
End If
Please note that I've not included any type of error handling.
Related
i'm pretty new to programming and i got stuck trying to write a program where you type in the name and prices of products and you get back the total, the name+ prices and the most expensive product. Everything works fine except showing the name of the most expensive product.
Here's what i've done
""
Public Class Mrj
Shared Sub main()
Dim i, n As Integer
Console.WriteLine("Enter the number of products")
n = Console.ReadLine()
Dim Products_name(n) As String
Dim Products_price(n), HT, TTC, TVA, max As Decimal
For i = 1 To n
Console.WriteLine("Enter the name of the product " & i)
Products_name(i - 1) = Console.ReadLine()
Console.WriteLine("Enter the price of the product " & i)
Products_price(i - 1) = Console.ReadLine()
HT = HT + Products_price(i - 1)
Next
For i = 1 To n
Console.WriteLine(Products_name(i - 1) & " " & Products_price(i - 1))
Next
TVA = 0.2 * HT
TTC = HT + TVA
Console.WriteLine("Total to pay " & TTC)
max = Products_price(0)
For i = 1 To n - 1
If max > Products_price(i) Then
Else
max = Products_price(i)
End If
Next
Console.WriteLine("The product the most expensive is" & max & Products_name(i))
End Sub
End Class
""
I think the problem is that you are using i to get the name of the most expensive product, but that index i is always i = n since you don't save the index of the maximum value.
You should add a new variable where you store the index everytime you get a new maximum value, and use it in the last line.
Your for loop should be something like this:
Dim max_index As Integer
For i = 1 To n - 1
If max > Products_price(i) Then
Else
max = Products_price(i)
max_index = i
End If
Next
Console.WriteLine("The product the most expensive is" & max & Products_name(max_index))
Try this out and check if it works.
Turn on Option Strict now and forever. Project Properties -> Compile tab. Also for future projects Tools -> Options -> Projects and Solutions -> VB Defaults
You cannot assume that a user will actually enter a number. Test with TryParse.
Arrays in vb.net are declared Products_name(upper bound). In this case that would be Products_name(n-1)
Instead of doing i - 1 for the indexes in the For loop, start our with For i = 0 to n-1
I decided to not use the parallel arrays. Instead I made a tiny class and declared a List(Of Product). I filled the list with the user input setting the Properties of the Product.
I used Linq instead of loops for sums and max. Not necessarily faster but can be accomplished in a single line of code.
I use interpolated strings to display results. When your string is preceded by a $, you can insert variables directly in the text surrounded by braces. The colon following Price indicates a formatting character. Here, I used a C for currency.
Public Class Product
Public Property Name As String
Public Property Price As Decimal
End Class
Sub main()
Dim ProductList As New List(Of Product)
Dim n As Integer
Console.WriteLine("Enter the number of products")
Integer.TryParse(Console.ReadLine, n)
For i = 1 To n
Dim p As New Product
Dim pr As Decimal
Console.WriteLine("Enter the name of the product " & i)
p.Name = Console.ReadLine()
Console.WriteLine("Enter the price of the product " & i)
Decimal.TryParse(Console.ReadLine, pr)
p.Price = pr
ProductList.Add(p)
Next
For Each p In ProductList
Console.WriteLine($"{p.Name} {p.Price:C}")
Next
Dim SubTotal As Decimal = ProductList.Sum(Function(item) item.Price)
Dim Tax As Decimal = 0.2D * SubTotal
Dim Total = SubTotal + Tax
Console.WriteLine($"Total to pay {Total:C}")
Dim Prod = ProductList.OrderByDescending(Function(p) p.Price).FirstOrDefault()
Console.WriteLine($"The product the most expensive is {Prod.Name} at {Prod.Price:C}")
Console.ReadKey()
End Sub
The following is an exercise I am having trouble with.
The button’s Click event procedure should display the number of integers from 14 to 23 in one of the labels and the sum of those integers in the other label. Code the procedure using the For…Next statement. Save the solution and then start and test the application. (The procedure should display the numbers 10 and 185.)
I'm able to display the sum 185 but not understanding how to display the amount of numbers (10) between 14 to 23. Any help is appreciated.
Public Class frmMain
Private Sub btnShow_Click(sender As Object, e As EventArgs) Handles btnShow.Click
Dim intSum As Integer
For intNum As Integer = 14 To 23
lblShow.Text = lblShow.Text & intNum.ToString & " "
intSum += intNum
lblSum.Text = intSum.ToString
Next
End Sub
End Class
Just declare sum and count local variables and increment them appropriately in the For. You need only update the Label.Text once after the calculations have been done
Dim intSum As Integer
Dim intCount As Integer
For intNum As Integer = 14 To 23
intSum += intNum
intCount += 1
Next
lblSum.Text = intSum.ToString()
lblShow.Text = intCount.ToString()
I understand your homework has the For requirement, but .NET has some functionality built in which can produce a list of numbers, sum them, and count them.
Dim start = 14
Dim finish = 23
Dim numbers = Enumerable.Range(start, finish - start + 1)
lblSum.Text = numbers.Sum().ToString()
lblShow.Text = numbers.Count().ToString()
Both methods produce your required output
display the number of integers from 14 to 23
This can be interpreted in a couple of ways:
Display the count of integers between the two numbers (e.g. 23 - 14)
Display each individual integer between the two numbers (e.g. 14, 15, 16, etc.)
If it is the former, then simply subtract the larger number from the smaller number and display that value in a label:
LabelIntegerCount.Text = (23 - 147).ToString()
If it is the latter, then inside of your For/Next loop append the currently iterated counter to the label:
For intNum As Integer = 14 To 23
LabelIntegerCount.Text &= intNum.ToString() & Environment.NewLine
' ...
Next
So I'm a beginner in vb class and am wondering how I can add up all products of Modnumber(variable name) Mod 2 so that i can attach them into one single line at the bottom of my listbox. What line should i add so the program runs like the pic below?
Dim number As Integer
Dim Modnumber As String
number = InputBox("I'm kindly asking you to tell me a number", "Number")
LstNumber.Items.Clear()
Do Until number = 1
Modnumber = number
LstNumber.Items.Add(number & vbTab & Modnumber Mod 2)
'each time it devides the number by two until number = 1
number \= 2
Loop
This is what I get
This is what I'm supposed to get in my lstbox
'capture your original input to use in the final result
Dim input = InputBox("I'm kindly asking you to tell me a number", "Number")
Dim number As Integer = input
Dim modNumber As Integer 'Changed this to a number
Dim result As New StringBuilder 'Used to store the product of doing Mod 2
LstNumber.Items.Clear()
Do Until number = 0 'loop until 0 instead of 1
modNumber = number Mod 2 'Do mod outside of LstNumber add so u can retain the value
LstNumber.Items.Add(number & vbTab & modNumber)
result.Insert(0, modNumber) 'Build your result string
number \= 2
Loop
'Add your additional stuff
LstNumber.Items.Add("Therefore")
LstNumber.Items.Add($"{input} = {result.ToString}") 'Original input plus built string
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.
I'm trying to randomize an array from numbers 0 to 51 using loops but I just cannot seem to pull it off. My idea was that
Generate a Random Number
Check if this random number has been used by storing the previous in an array
If this random number has been used, generate new random number until it is not a duplicate
If it's not a duplicate, store it
My attempt:
Dim list(51) As Integer
Dim templist(51) As Integer
For i As Integer = 0 To 51 Step 1
list(i) = i
Next i
Do While counter <= 51
p = rand.Next(0, 52)
templist(counter) = p
For n As Integer = 0 To 51 Step 1
p = rand.Next(0, 52)
If templist(n) = p Then
Do While templist(n) = p
p = rand.Next(0, 52)
Loop
templist(n) = p
Else
templist(n) = p
End If
Next
counter += 1
Loop
For n As Integer = 0 To 51 Step 1
ListBox1.Items.Add(templist(n))
Next
It will be a lot easier if you just have a list of all of the possible numbers (0 to 51 in your case), then remove the number from the list so it can't be picked again. Try something like this:
Dim allNumbers As New List (Of Integer)
Dim randomNumbers As New List (Of Integer)
Dim rand as New Random
' Fill the list of all numbers
For i As Integer = 0 To 51 Step 1
allNumbers.Add(i)
Next i
' Grab a random entry from the list of all numbers
For i As Integer = 0 To 51 Step 1
Dim selectedIndex as Integer = rand.Next(0, (allNumbers.Count - 1) )
Dim selectedNumber as Integer = allNumbers(selectedIndex)
randomNumbers.Add(selectedNumber)
allNumbers.Remove(selectedNumber)
' Might as well just add the number to ListBox1 here, too
ListBox1.Items.Add(selectedNumber)
Next i
If your goal is to get the numbers into ListBox1, then you don't even need the "randomNumbers" list.
EDIT:
If you must have an array, try something like this:
Function RandomArray(min As Integer, max As Integer) As Integer()
If min >= max Then
Throw New Exception("Min. must be less than Max.)")
End If
Dim count As Integer = (max - min)
Dim randomNumbers(count) As Integer
Dim rand As New Random()
' Since an array of integers sets every number to zero, and zero is possibly within our min/max range (0-51 here),
' we have to initialize every number in the array to something that is outside our min/max range.
If min <= 0 AndAlso max >= 0 Then
For i As Integer = 0 To count
randomNumbers(i) = (min - 1) ' Could also be max + 1
Next i
End If
Dim counter As Integer = 0
' Loop until the array has count # of elements (so counter will be equal to count + 1, since it is incremented AFTER we place a number in the array)
Do Until counter = count + 1
Dim someNumber As Integer = rand.Next(min, max + 1)
' Only add the number if it is not already in the array
If Not randomNumbers.Contains(someNumber) Then
randomNumbers(counter) = someNumber
counter += 1
End If
Loop
Return randomNumbers
End Function
This is good enough for your assignment, but the computer scientist in my hates this algorithm.
Here's why this algorithm is much less desirable. If zero is in your range of numbers, you will have to loop through the array at least 2N times (so 104+ times if you are going from 0 to 51). This is a best case scenario; the time complexity of this algorithm actually gets worse as the range of numbers scales higher. If you try running it from 0 to 100,000 for example, it will fill the first few thousand numbers very quickly, but as it goes on, it will take longer and longer to find a number that isn't already in the list. By the time you get to the last few numbers, you could potentially have randomly generated a few trillion different numbers before you find those last few numbers. If you assume an average complexity of 100000! (100,000 factorial), then the loop is going to execute almost ten to the half-a-millionth power times.
An array is more difficult to "shuffle" because it is a fixed size, so you can't really add and remove items like you can with a list or collection. What you CAN do, though, is fill the array with your numbers in order, then go through a random number of iterations where you randomly swap the positions of two numbers.
Do While counter <= 51
p = rand.Next(0, 52)
While Array.IndexOf(list, p) = -1
p = rand.Next(0, 52)
End While
counter += 1
Loop
Haven't written VB in about 5 years, but try this out:
Function GetRandomUniqueNumbersList(ByVal fromNumber As Integer, ByVal toNumber As Integer) As List(Of Integer)
If (toNumber <= fromNumber) Then
Throw New ArgumentException("toNumber must be greater than fromNumber", toNumber)
End If
Dim random As New Random
Dim randomNumbers As New HashSet(Of Integer)()
Do
randomNumbers.Add(random.Next(fromNumber, toNumber))
Loop While (randomNumbers.Count < toNumber - fromNumber)
Return randomNumbers.ToList()
End Function
Ok, that was painful. Please someone correct it if I made any mistakes. Should be very quick because it's using a HashSet.
First response to forum on stackoverflow - be gentle.
I was looking for a way to do this but couldn't find a suitable example online.
I've had a go myself and eventually got this to work:
Sub addUnique(ByRef tempList, ByVal n, ByRef s)
Dim rand = CInt(Rnd() * 15) + 1
For j = 0 To n
If tempList(j) = rand Then
s = True
End If
Next
If s = False Then
tempList(n) = rand
Else
s = False
addUnique(tempList, n, s)
End If
End Sub
Then call the sub using:
Dim values(15) As Byte
Dim valueSeen As Boolean = False
For i = 0 To 15
addUnique(values, i, valueSeen)
Next
This will randomly add the numbers 1 to 16 into an array. Each time a value is added, the previous values in the array are checked and if any of them are the same as the randomly generated value, s is set to true. If a value is not found (s=false), then the randomly generated value is added. The sub is recursively called again if s is still true at the end of the 'For' loop. Probably need 'Randomize()' in there somewhere.
Apologies if layout is a bit wobbly.