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Using File.IO.StreamWriter to create a text file

   Private Sub WriteText1(ByVal fn As String)
        Dim sw As New StreamWriter(fn)
        For xx = 1 To 5
            sw.WriteLine("This is a line of text")
        Next
        sw.Close()
    End Sub

This is one of the simplest ways to create a text file. If the file already exist it is overwritten.

Just:

Open the file using StreamWriter
Write text to the file with Write or Writeline
Close the file

Using System.IO.StreamReader to read a text file

  Private Sub ReadText1(ByVal fn As String)
        Dim sr As New StreamReader(fn)
        Dim sdx As String
        Do
            sdx = sr.ReadLine()
            Console.WriteLine(sdx)
        Loop Until sr.EndOfStream
        sr.Close()
    End Sub

One of the simplest possible ways to read a text file
Just:

Open file with StreamReader.New(filename)
Loop through file with ReadLine
Save the string from ReadLine
Keep looping until StreamReader.EndOfStream
Close the file

Using File.WriteAllLines(path string, string())

 Private Sub WriteText2(ByVal path As String)
        Dim buffer(5) As String
        For xx = 0 To 4
            buffer(xx) = "This is a test " + xx.ToString
        Next
        File.WriteAllLines(path, buffer)
 End Sub

This one is simple as well.

Create a string array to hold your data
Pass the file name and string array to File.WriteAllLines
File.WriteAllLines closes the file for you

Using File.ReadAllLines(path string)

  Private Sub ReadText2(ByVal path As String)
        Dim buffer() As String
        buffer = File.ReadAllLines(path)
    End Sub

Dim a string array to hold your data
call File.ReadAllLines to fill it
File.ReadAllLines closes the file for you

Using File.WriteAllText(path string, string array)

 Private Sub WriteText3(ByVal path As String)
        Dim buffer As String
        buffer = "this is a test"
        File.WriteAllText(path, buffer)
    End Sub

Simply writes the text string passed in to a text file whose name is defined in the path statement.

Using string = File.ReadAllText(path string)

Private Sub ReadText3(ByVal path As String)
        Dim buffer As String
        buffer = File.ReadAllText(path)
    End Sub

File.ReadAllText does not return an array of strings, but puts the whole text file in the one string. If the file had been saved as individual lines, this routine will return one long string with all lines appended together

Using File.IO.StreamWriter to append text to a file

 Private Sub WriteText1Append(ByVal path As String,append as boolean)
        Dim sw As New StreamWriter(path, append) ' assume append = True
        For xx = 1 To 5
            sw.WriteLine("This is a line of text " + xx.ToString)
        Next
        sw.Close()
    End Sub

The second parameter controls whether to append to the file or not. If the second parameter is false then it is equivelent to WriteText1(path) in the first example.

11/14/2015