Programming Fundamentals/Files/VB.NET

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files.vb[edit | edit source]

' This program creates a file, adds data to the file, displays the file,
' appends more data to the file, displays the file, and then deletes the file.
' It will not run if the file already exists.
'
' References:
'     https://www.mathsisfun.com/temperature-conversion.html
'     https://en.wikibooks.org/wiki/Visual_Basic_.NET

Public Module Files
 
    Sub Main()
        Const FILENAME As String = "~file.txt"

        If(System.IO.File.Exists(FILENAME)) Then
            System.Console.WriteLine("File already exists.\n")
        Else
            CreateFile(FILENAME)
            ReadFile(FILENAME) 
            AppendFile(FILENAME)
            ReadFile(FILENAME)
            DeleteFile(FILENAME)
        End If
    End Sub

    Sub CreateFile(Filename As String)
        Dim File As System.IO.StreamWriter
        Dim C As Single
        Dim F As Single
        
        File = System.IO.File.CreateText(Filename)
        File.WriteLine("C   F")
        For C = 0 To 50
            F = C * 9 / 5 + 32
            File.WriteLine(C.ToString() + "   " + F.ToString())
        Next
        File.Close()
    End Sub
    
    Sub ReadFile(Filename As String)
        Dim File As System.IO.StreamReader
        Dim Line As String
        
        File = System.IO.File.OpenText(Filename)
        Do While True 
            Line = File.ReadLine()
            If Line = Nothing Then
                Exit Do
            End If
            Console.WriteLine(Line)
        Loop
        File.Close()
        Console.WriteLine("")
    End Sub
    
    Sub AppendFile(Filename As String)
        Dim File As System.IO.StreamWriter
        Dim C As Single
        Dim F As Single
        
        File = System.IO.File.AppendText(Filename)
        For C = 51 To 100
            F = C * 9 / 5 + 32
            File.WriteLine(C.ToString() + "   " + F.ToString())
        Next
        File.Close()
    End Sub
    
    Sub DeleteFile(Filename As String)
        System.IO.File.Delete(Filename)
    End Sub
End Module

Try It[edit | edit source]

Copy and paste the code above into one of the following free online development environments or use your own VB.NET compiler / interpreter / IDE.

See Also[edit | edit source]