VB program to calculate grades - vb.net

Question

So I am working on a program that will ask for the number of assignments, say 20, then run through a loop that many times asking for the total points earned on each assignment as well as the total points possible to get the final grade. For example if the user put in 2 assignments with assignment 1 earning 48 points out of 50 and assignment 2 earning 35 points out of 40 the program would display the grade as 92.
So far here is what I have:
Public Class Form1
Private Sub btnExit_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnExit.Click
Me.Close()
End Sub
Private Sub btnCalculate_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCalculate.Click
Dim amountAssignments As Integer
Dim pointsEarned As Integer = 0
Dim pointsEarnedTotal As Integer = 0
Dim pointsPossible As Integer = 0
Dim pointsPossibleTotal As Integer = 0
Dim Assignment As Integer = 1
Integer.TryParse(txtAmount.Text, amountAssignments)
Do Until Assignment > amountAssignments
txtAmount.Text = String.Empty
lblAmount.Text = "Enter Points Given on Assignment " & Assignment & ":"
Integer.TryParse(txtAmount.Text, pointsEarned)
pointsEarnedTotal = pointsEarnedTotal + pointsEarned
lblAmount.Text = "Enter Points Possible on Assignment " & Assignment & ":"
Integer.TryParse(txtAmount.Text, pointsPossible)
pointsPossibleTotal = pointsPossibleTotal + pointsPossible
Assignment = Assignment + 1
Loop
lblAmount.Text = "Enter the amount of Assignments: "
lblGrade.Text = (pointsEarnedTotal / pointsPossibleTotal)
End Sub
End Class
syntax is correct but when the program is run and the number of assignments put in and calculate entered the program displays the grade as NaN with no other input requested.
Could use another set of eye(s) to look over this and tell me where i screwed up logically.
Thank you in advance!

Answer 1

This program seems to not have some sort of user intervention when the loop starts. What I would do is surely have the user enter the amount of assignments on the textbox and then from there would ask the user to enter marks from an input box separated by a slash e.g I enter 45/50 so after input the program finds the index of "/",all characters before the '/' are the pointsEarned and can be added to the pointsEarnedTotal while all the characters after the '/' are placed in the pointsPossible and added to the pointsPossibleTotal
Try this and tell me how it goes...give me points if it works
` Private Sub butGetMarks_Click(sender As System.Object, e As System.EventArgs) Handles butGetMarks.Click
Dim assignments As Integer = 0
Dim totalAssignments As Integer
Integer.TryParse(txtAssignments.Text, totalAssignments)
Dim pointsEarned As Double = 0
Dim pointsEarnedTotal As Double = 0
Dim possibleEarned As Double = 0
Dim possibleEarnedTotal As Double = 0
Dim temp As String
For i As Integer = 1 To totalAssignments
temp = InputBox("Enter marks per assignment separated by /")
Dim i1 As Integer
i1 = temp.IndexOf("/") 'read index of /
pointsEarned = temp.Substring(0, i1) 'read from start until / character
possibleEarned = temp.Substring(i1 + 1) 'read from after / character onwards
'add to totals
possibleEarnedTotal += possibleEarned
pointsEarnedTotal += pointsEarned
Next i
MessageBox.Show(pointsEarnedTotal & "/" & possibleEarnedTotal)
End Sub`