New to programming language, need help to read a .dat file into array Vs VB, console .net framework - vb.net

Question

I am trying to read from a data file called TXT.dat and store the circled values into a separate array's using the type of commands I have used. I cannot use streamreader,streamwriter this is what I am learning at university but we were taught to read an array not certain values as I will be tested using a file which has
2 factorial values from a single file and store int two arrays.
I have spent hours trying before going to paid sites who always answer with i/o streamreader which doesnt help
.dat file i created to practice
MY CODE
Sub Main()
Const i_val As Integer = 6
Dim j As Integer = 6 'loop readers
Dim Arayn_Fact(i_val - 1) As Double 'array for 2nd value per line
Dim Aray_Fact2n(j - 1) As Double 'array for 4th value per line
Read_Values(i_val - 1, Arayn_Fact)
End Sub
Sub Read_Values(ByVal i As Integer, ByRef _A() As Double)
Dim fid1 As Integer = FreeFile()
Dim fid2 As Integer = FreeFile() + 1
Dim tmp As Double
FileOpen(fid1, "TXT.dat", OpenMode.Input, OpenAccess.Read)
For i = 0 To 5 Step 1
Input(fid1, tmp)
Input(fid1, _A(i))
Next i
FileClose(fid1)
Console.ReadKey()
End Sub

Answer 1

Without getting too fancy, here's some very basic code to do what you've outlined:
Sub Main()
Dim fileName As String = "txt.dat"
Dim Aray_Fact2() As Integer 'array for 2nd value per line
Dim Aray_Fact4() As Integer 'array for 4th value per line
Dim list2 As New List(Of Integer)
Dim list4 As New List(Of Integer)
Dim lines() As String = System.IO.File.ReadAllLines(fileName)
For Each line As String In lines
Dim values() As String = line.Split(",")
If values.Length >= 3 Then
Dim f2, f4 As Integer
If Integer.TryParse(values(1), f2) AndAlso Integer.TryParse(values(3), f4) Then
list2.Add(f2)
list4.Add(f4)
Else
Console.WriteLine("Invalid value in line: " & line)
End If
Else
Console.WriteLine("Invalid number of entries in line: " & line)
End If
Next
Aray_Fact2 = list2.ToArray
Aray_Fact4 = list4.ToArray
Console.WriteLine("Aray_Fact2: " & String.Join(",", Aray_Fact2))
Console.WriteLine("Aray_Fact4: " & String.Join(",", Aray_Fact4))
Console.Write("Press Enter to Quit...")
Console.ReadLine()
End Sub
If you are completely against the use of Lists and ToArray, then you'd have to read the file TWICE. Once to determine how many lines are in the file so you can dimension the arrays to the correct size. Then another time to actually read the values and populate the arrays.

Answer 2

First, some style things. Passing the array ByRef is incorrect. Arrays are already reference types, and so passing ByVal still passes the reference to the array object. But don't even pass the array in the first place. It's better practice to let the Read_Values() method create and return the array to the calling function.
And no one uses that ancient/ganky FileOpen() API anymore. I mean that. NO. ONE. It's not even appropriate for teaching, as the Stream types are closer to what the low level operating system/file system are doing. If you can't use StreamReader and friends, there are still better options out there.
Sub Main()
Dim Array_Fact() As Double = Read_Values("TXT.dat", 1)
Dim Array_Fact2n() As Double = Read_Values("TXT.dat", 3)
Console.ReadKey(True)
End Sub
Function Read_Values(filePath As String, position As Integer) As Double()
Dim lines() As String = File.ReadAllLines(filePath) 'Look Ma, no StreamReader
Dim result(lines.Length - 1) As Double
For i As Integer = 0 To Lines.Length - 1
result(i) = Double.Parse(lines(i).Split(",")(position).Trim())
Next line
Return result
End Function
But what I'd really do is keep the 2nd and 4th values in the same collection and read everything in one pass through the file. This uses features like Generics, Tuples, Lambdas+Linq, and more that you won't get to for some time, but I feel like it's useful to show you where you're going:
Sub Main()
Dim Facts = Read_Values("TXT.dat")
Console.WriteLine(String.Join(",",Facts.Select(Function(f) $"({f.Item1}:{f.Item2})")))
Console.ReadKey(True)
End Sub
Function Read_Values(filePath As String) As IEnumerable(Of (Double, Double))
Return File.ReadLines(filePath).Select(
Function(line) 'Poor man's CSV. In real code, I'd pull in a CSV parser from NuGet
Dim fields = line.Split(",")
Return (Double.Parse(fields(1).Trim()), Double.Parse(fields(3).Trim()))
End Function
)
End Function