How to read a delimited line of strings and ints and extract them for processing in VB

Question

Hi, I have the following text file (ExamMarks.txt)

John, 85, 95, 90

Micheal, 60, 75, 75

I want to extract a line and take the Name and separately and the ints separately. Then I want to print the name and the average of the numbers like this in a label:

John's average is 90

Micheal's average is 70

So far I can only display what is in the text file in a label (see below):

Dim FILE_NAME As String = "C:\ExamMarks.txt"
Dim TextLine As String

If System.IO.File.Exists(FILE_NAME) = True Then

  Dim objReader As New System.IO.StreamReader(FILE_NAME)

  Do While objReader.Peek() <> -1
    TextLine = TextLine & objReader.ReadLine & vbNewLine

  Loop

  lblResults.Text = TextLine

Else

  MsgBox("File Does Not Exist")

End If

Any help is appreciated.

Answer 1

Do this processing for each of the lines in the file. It assumes that the name is always the first word in the string, then it calculates the average of all the numbers in the string.

'Split the test string on commas
Dim strScores() As String = strTest.Split(",".ToCharArray)
Dim strWord As String
Dim intTotalScore As Integer
Dim intCountOfScores As Integer
Dim intAverageScore As Integer

'Name is the first word in the line
strName = strScores(1).Trim

For Each strWord In strScores
    If IsNumeric(strWord) Then
        intTotalScore = intTotalScore + Int(strWord.Trim)
        intCountOfScores = intCountOfScores + 1
    End If
Next

'Calculate the average    
intAverageScore = intTotalScore / intCountOfScores

Answer 2

You can do all this much more briefly with some more modern code:

1. Use the built-in TextFieldParser to read the comma-separated file, and access each row as a string array. It's simpler and more robust than using Split.
2. And then use IEnumerable extension methods to calculate the average all in one line.
   a. Skip(1) skips the first entry.
   b. Average() lets you convert the remaining entries to Double and then take the average.

Like this:

  Sub Main()    
    Using MyReader As New  _
      Microsoft.VisualBasic.FileIO.TextFieldParser("ExamMarks.txt")
      MyReader.TextFieldType = FileIO.FieldType.Delimited
      MyReader.SetDelimiters(",")

      Dim currentRow As String()
      While Not MyReader.EndOfData
        Try
          ' Read row as an array of strings '
          currentRow = MyReader.ReadFields()
          ' Calculate average '
          Dim dAverage As Double = _
            currentRow.Skip(1).Average(Function(s) Convert.ToDouble(s))
          ' Write out result '
          Console.WriteLine(currentRow(0) & "'s average is " & _
            Convert.ToString(dAverage))
        Catch ex As Microsoft.VisualBasic.FileIO.MalformedLineException
          MsgBox("Line " & ex.Message & "is not valid and will be skipped.")
        End Try
      End While
    End Using
    Console.ReadLine()
  End Sub