CSV. A comma-separated values file can be handled in a variety of ways in a VB.NET program. Often the best approach is to use the System.IO namespace and parse the file with String functions.

By calling Split on each line as we read it into memory, we can separate out fields. The strings returned could be added to a List or stored in a Class instance.

Example. To begin, make sure to change the path in the Main Sub to a CSV file that exists. The path is relative to the home directory on the computer.

Imports System.IO

Module Module1

    Sub HandleFile(path As String)
        ' Step 1: read lines from the file.
        For Each line in File.ReadLines(path)
            ' Step 2: separate each line on the comma char.
            Dim parts = line.Split(","c)

            ' Step 3: print out the parts of the line.
            For Each value in parts
                Console.WriteLine("FIELD: {0}", value)
            Next
        Next
    End Sub

    Sub Main()
        HandleFile("programs/example.txt")
    End Sub
    
End Module
FIELD: Field1
FIELD: Field2
FIELD: Field3
FIELD: Field4
FIELD: 100
FIELD: 200
FIELD: 300

More complex formats can be handled in VB.NET, like JSON or even binary files, but CSV is often a good choice. It can be read and edited by humans, and processed with String methods in programs.