Counter

[Jblake00]

I could use a little bit of input on creating a way to keep up with counting the number of people that have 2 scores in a text file.
then how I get it to do the math correctly.
I know it should be something simalar to
Total score += score1 + score2
But how do I make keep up with any amount of people in the text file and then divide it properly?

 

[AndreRyan]

This sounds simple but youve presented your problem in a confusing way.

Do you mean reading a pair of numbers from a file and then adding them together?

 

[Jblake00]

Yes I do. But then I have to keep up with the number of times it does it and the figure out how to divide it.
I kind of got the idea in my head but I am missing something.

 varEveryonesGrade += Math.Round(varEveryonesGrade / 3)

That works when the text file only contains 3 people. And when you have to step through the stream reader for every line that is read. Such as.

        Start = my.ReadLine
        strStudent = Start.Substring(0, 11)
        Grade1 = Start.Substring(12, 4)
        Grade2 = Start.Substring(16, 4)
        varAverage = Math.Round((Grade1 + Grade2) / 2, 0)
        txtDsplyClsAvr.Text = "The class average is " & CStr(varEveryonesGrade)

And repeat the process for each person in the text file.
But a loop can do it by only writing the code once, But I need to get my counter down.Here is what I got so far, Also my msgBox doesnt display when the floppy isnt in the drive.

 Dim my As IO.StreamReader
        my = IO.File.OpenText("A:\grades.txt")
        
        Dim fmtStr As String = "{0,11}{1,4} {2,8}  {3,6}     {4,6}"
        Dim strStudent, Start As String, strLetterGrade As String
        Dim Grade1, Grade2, total As Double
        Dim varEveryonesGrade As Double
        Dim varAverage As Double
        varEveryonesGrade = 0
        varAverage = 0


        Message box not showing up when file isnt in the drive.
               If IO.File.Exists("A:\grades.txt") = True Then

            Do While my.Peek <> -1
                 strStudent = strStudent
                Start = my.ReadLine
                strStudent = Start.Substring(0, 11)
                Grade1 = Start.Substring(12, 4)
                Grade2 = Start.Substring(16, 4)
                varAverage += 1

                varAverage = Math.Round((Grade1 + Grade2) / 2, 0)


                varEveryonesGrade += varAverage + total
                varEveryonesGrade += Math.Round((Grade1 + Grade2) &  varAverage / varEveryonesGrade))


                varEveryonesGrade += 1
                txtDsplyClsAvr.Text = "The class average is " & CStr(varEveryonesGrade)


                  Math.Round(varAverage)
                need to use case statements with this one!
I should be able to figure that out so no one needs to 
bother with it unless they just so want to.. 
                If varAverage >= 90 Then
                    strLetterGrade = "A"


                ElseIf varAverage >= 80 Then
                    strLetterGrade = "B"

                ElseIf varAverage >= 70 Then
                    strLetterGrade = "C"

                ElseIf varAverage >= 60 Then
                    strLetterGrade = "D"

                ElseIf varAverage >= 50 Then
                    strLetterGrade = "F"
                End If

                lstGtGrds.Items.Add(String.Format(fmtStr, strStudent, Grade1, Grade2, varAverage, strLetterGrade))
                
                
            Loop

        ElseIf IO.File.Exists("A:\grades.txt") = False Then

            MsgBox("Try putting in the disk that has grades.txt on it!", , "Missing Disk")




        End If
        my.Close()

    End Sub

I hope that will clarify what I am trying to accomplish.

 

[PlausiblyDamp]

Just somethings you may have missed in there

varAverage += 1
varAverage = Math.Round((Grade1 + Grade2) / 2, 0)

the second line will always over write the contents of varAverage - the +1 you doing before it is not going to have any effect.

also in the line

varEveryonesGrade += Math.Round((Grade1 + Grade2) &  varAverage / varEveryonesGrade))

what are you trying to do - you seem to be mixing math calculations + and / with string concatenation - &. Is that really what you want?

 

[Jblake00]

Hmm I change a little code, but came up with a weird calculation.
The class average is 505, that should come out to be
The class average is 77. Here is what I tryed

varEveryonesGrade += varAverage + total
                total += (Grade1 + Grade2) & (varAverage / varEveryonesGrade)
                total = Math.Round(varEveryonesGrade, 2)

 

[PlausiblyDamp]

The problem could be the & it will calculate the (Grade1 + Grade2) bit as a number, then calculate the (varAverage / varEveryonesGrade) as a number and then concatenate the two together as if they were strings.

If you put a breakpoint on the line

total += (Grade1 + Grade2) & (varAverage / varEveryonesGrade)

what does the results of (Grade1 + Grade2) and (varAverage / varEveryonesGrade) look like and how do they compare to the calculated total?

 

[Jblake00]

Ok now I got

Start = my.ReadLine
                strStudent = Start.Substring(0, 11)
                Grade1 = Start.Substring(12, 4)
                Grade2 = Start.Substring(16, 4)
                varAverage = Math.Round((Grade1 + Grade2) / 2, 0)
                varAverage += varEveryonesGrade
                sum = Math.Round(varEveryonesGrade \ varAverage)
txtDsplyClsAvr.Text = "The class average is " & CStr(varEveryonesGrade)

But the result displayed in the text box is wrong. It says
"The class average is 0" It should give an average of 76 or 77?
Hmm I bet I need to be dividing this by the number of students.
That is probably what I need to be keeping the count on?

 

[PlausiblyDamp]

again

varAverage = Math.Round((Grade1 + Grade2) / 2, 0)
varAverage += varEveryonesGrade

you are asigning a value to a variable in one line and then simply overwriting it in the next. You seem to be making the problem a lot more confusing and convuleted than it really is. What does the file look like and what are you trying to do?

As far as I can tell you want to average a grade for a student from 2 grades and then average this value for X number of students - correct?

 

[Jblake00]

Well at least I accomplished one thing.
I fixed the message box problem.
All I have to do way move the line.
my = IO.File.OpenText("A:\grades.txt")
from under the Dim my IOSteamReader
to under the line If IO.File.Exists("A:\grades.txt") like this

If IO.File.Exists("A:\grades.txt") 
my = IO.File.OpenText("A:\grades.txt")

now the messagebox executes if the disk is not in the drive!
if I could just figure out the math.I know it is an algebraic type of problem or I think it is. I drew it on paper. Here is my idea of the thing
grade1 + grade2 / 2 = average>
grade1 + grade2 / 2 = average>>> =allAverages / sum
grade1 + grade2 / 2 = average>
Which in this case the sum would be 3, but I need to figure out a way to figure out how to keep track of the sum. Just in case more students are added to the text file. Sorry this post is getting so long.

 

[PlausiblyDamp]

grade1 + grade2 /2 -> average of one student.
average of all students / number of students = overall average (I think - my stats are a bit rusty)

you could simply add a counter to the routine and every time you read a students details in just increment it.

 

[Jblake00]

Ok I am getting a lot closer I think? Here is my code now.

Private Sub btnGtGrades_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnGtGrades.Click
        Dim my As IO.StreamReader      
        Dim fmtStr As String = "{0,11}{1,4} {2,8}  {3,6}     {4,6}"
        Dim strStudent, Start As String, strLetterGrade As String
        Dim Grade1, Grade2, total As Double
        Dim varEveryonesGrade As Double
        Dim varAverage As Double
        Dim sum As Integer

              varAverage = 0
                      sum = 0
                If IO.File.Exists("A:\grades.txt") Then
            my = IO.File.OpenText("A:\grades.txt")
            Do While my.Peek <> -1

                Start = my.ReadLine
                strStudent = Start.Substring(0, 11)
                Grade1 = Start.Substring(12, 4)
                Grade2 = Start.Substring(16, 4)
                varAverage = Math.Round((Grade1 + Grade2) / 2, 0)
                varEveryonesGrade += varAverage
                sum += 1
                varEveryonesGrade = Math.Round(varEveryonesGrade / sum)

                txtDsplyClsAvr.Text = "The class average is " & CStr(varEveryonesGrade)

                              
                Select Case varAverage
                    Case Is >= 90
                        strLetterGrade = "A"
                    Case Is >= 80
                        strLetterGrade = "B"
                    Case Is >= 70
                        strLetterGrade = "C"
                    Case Is >= 60
                        strLetterGrade = "D"
                    Case Is >= 50
                        strLetterGrade = "F"
                End Select
                lstGtGrds.Items.Add(String.Format(fmtStr, strStudent, Grade1, Grade2, varAverage, strLetterGrade))

            Loop

        Else

            MsgBox("Try putting in the disk that has grades.txt on it!, , Missing Disk")




        End If
        my.Close()

    End Sub
End Class

Everything works except I get an unexpected result in the text box where the class average is displayed. The txtBox displays the meassage, "The class average is 53" and it should be "77". I suspect this has something to do with counting my sum. Hmm by the way it is calculating, it is like it is being divided by 4.5 or something close to that when it should be divided by 3????

 

[PlausiblyDamp]

try only doing the line

varEveryonesGrade = Math.Round(varEveryonesGrade / sum)

after the loop as you are currently going to be shifting the value lower by averaging it every iteration of the loop.

The first and second time the varEveryOnesGrade will be correct, but on the third loop you will have divided by one extra time, and again on the 4th etc.

 

[Jblake00]

The problem was the line was in the wrong place