Programming Tutorials

Vb.net text reader

By: Issac in VB.net Tutorials on 2009-01-31  

StreamReader and StreamWriter are actually derived from Textreader and TextWriter, they are another way to read and write to a file but they are not stream classes.

Imports System.IO
Public Class Form1
    Private Sub Button1_Click(ByVal sender As System.Object, _
ByVal e As System.EventArgs) Handles Button1.Click
        Try
            Dim line As String
            Dim readFile As System.IO.TextReader = New _
	StreamReader("C:\TextReader.txt")
            While True
                line = readFile.ReadLine()
                If line Is Nothing Then
                    Exit While
                Else
                    MsgBox(line)
                End If
            End While
            readFile.Close()
            readFile = Nothing
        Catch ex As IOException
            MsgBox(ex.ToString)
        End Try
    End Sub
End Class

When you execute this program the TextReader read the file line by line.

The following code reads the entire content in a file into string using TextReader.

imports System.IO
Public Class Form1
    Private Sub Button1_Click(ByVal sender As System.Object, _
		ByVal e As System.EventArgs) Handles Button1.Click
        Try
            Dim line As String
            Dim readFile As System.IO.TextReader = New _
					StreamReader("C:\Test1.txt")
            line = readFile.ReadToEnd()
            MsgBox(line)
            readFile.Close()
            readFile = Nothing
        Catch ex As IOException
            MsgBox(ex.ToString)
        End Try
    End Sub
End Class

When you execute this code, TextReader reads the entire file in one stretch.