File.OpenText Method In VB.NET

This article explains how to open an existing UTF-8 encoded text file for reading.
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File.OpenText Method

The OpenText method opens an existing UTF-8 encoded text file for reading. The OpenText method takes a file name as a parameter and returns a StreamReader object.

Dim reader As StreamReader = fi.OpenText()

Once we have a StreamReader object, we can use its Read or ReadLine methods to read the contents. The ReadLine method reads one line at a time. The following code snippet loops through the entire content of a SteamReader and reads and prints one line at a time.

While (InlineAssignHelper(s, reader.ReadLine())) IsNot Nothing

            Console.WriteLine(s)

End While

The following lists the complete code sample.

Imports System.Text

Imports System.IO

Module Module1

    Sub Main()

        Dim fileName As String = "C:\Temp\MaheshTXFITx.txt"

        Dim fi As New IO.FileInfo(fileName)

        ' If file does not exist, create file

        If Not fi.Exists Then

            'Create the file.

            Using fs As FileStream = fi.Create()

                Dim info As [Byte]() = New UTF8Encoding(True).GetBytes("File Start")

                fs.Write(info, 0, info.Length)

            End Using

        End If

        Try

            Using reader As StreamReader = fi.OpenText()

                Dim s As String = ""

                While (InlineAssignHelper(s, reader.ReadLine())) IsNot Nothing

                    Console.WriteLine(s)

                End While

            End Using

        Catch Ex As Exception

            Console.WriteLine(Ex.ToString())

        End Try

    End Sub

    Private Function InlineAssignHelper(Of T)(ByRef target As T, ByVal value As T) As T

        target = value

        Return value

    End Function

End Module

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