Importing tab delimited file into array

Question

I am needing to import a tab delimited text file that has 11 columns and an unknown number of rows (always minimum 3 rows).

I would like to import this text file as an array and be able to call data from it as needed, throughout my project. And then, to make things more difficult, I need to replace items in the array, and even add more rows to it as the project goes on (all at runtime).

Hopefully someone can suggest code corrections or useful methods. I'm hoping to use something like the array style sMyStrings(3,2), which I believe would be the easiest way to control my data.

Imports System.IO
Imports Microsoft.VisualBasic.FileIO

Public Class Main
    Dim strReadLine As String

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
    Dim sReader As IO.StreamReader = Nothing
    Dim sRawString As String = Nothing
    Dim sMyStrings() As String = Nothing
    Dim intCount As Integer = -1
    Dim intFullLoop As Integer = 0

    If IO.File.Exists("C:\MyProject\Hardware.txt") Then     ' Make sure the file exists
        sReader = New IO.StreamReader("C:\MyProject\Hardware.txt")
    Else
        MsgBox("File doesn't exist.", MsgBoxStyle.Critical, "Error")
        End
    End If

    Do While sReader.Peek >= 0  ' Make sure you can read beyond the current position
        sRawString = sReader.ReadLine()     ' Read the current line
        sMyStrings = sRawString.Split(New Char() {Chr(9)})      ' Separate values and store in a string array

        For Each s As String In sMyStrings      ' Loop through the string array
            intCount = intCount + 1             ' Increment
            If TextBox1.Text <> "" Then TextBox1.Text = TextBox1.Text & vbCrLf ' Add line feed
            TextBox1.Text = TextBox1.Text & s   ' Add line to debug textbox
            If intFullLoop > 14 And intCount > -1 And CBool((intCount - 0) / 11 Mod 0) Then
                cmbSelectHinge.Items.Add(sMyStrings(intCount))
            End If
        Next
        intCount = -1
        intFullLoop = intFullLoop + 1
    Loop
End Sub

Answer 1

First I'd like to mention a style point. Ditch the hungarian notation. You don't need it. It often isn't maintained, so they tend to lie. when they are, it's a bit of a pain to find/replace your variable names. sReader should just be reader, intCount should just be count and so on.

I like that you're taking advantage of the single line variable declaration & assignment.

You should be using a few constants for your data file though. This reduces code duplication and makes it easier to change down the road.

const dataFilePath As String = "C:\MyProject\"
const dataFileName As String = "Hardware.txt"
const dataFile As String = dataFilePath & dataFileName

Now your code would look like this.

If IO.File.Exists(dataFile) Then     ' Make sure the file exists
    reader = New IO.StreamReader(dataFile)
Else
    '....

I don't see anything inherently wrong about your method of processing the file line by line. It's essentially no different from working in a 2 dimensional array. You may want to find out if you can read the whole file at once and use one anyway. I bet there would be a performance benefit.

What I do notice about your loops is the heavy reliance on Magic Numbers.

Go ahead and declare another constant TabChar and set it equal to Chr(9). And here:

        If intFullLoop > 14 And intCount > -1 And CBool((intCount - 0) / 11 Mod 0) Then
            cmbSelectHinge.Items.Add(sMyStrings(intCount))
        End If

What is 14? What is 11? Find appropriate names for them. It makes your code easier to read and easier to change/maintain later.

Further Reading on Naming Conventions

Answer 2

One way to hold all your data is with a DataTable. This gives you a collection of rows and each row has an ItemArray collection. Here's and example from a different post:

Dim sr As New IO.StreamReader(filename)
Dim dt As New DataTable
Dim newline() As String = sr.ReadLine.Split(","c)
dt.Columns.AddRange({New DataColumn(newline(0)), _
                     New DataColumn(newline(1))})
While (Not sr.EndOfStream)
    newline = sr.ReadLine.Split(","c)
    Dim newrow As DataRow = dt.NewRow
    newrow.ItemArray = {newline(0), newline(1)}
    dt.Rows.Add(newrow)
End While
DataGridView1.DataSource = dt