VB.Net Tutorial/Stream File/StreamReader

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Check Exception in file reading

Imports System.IO
Imports System
public class Test
   public Shared Sub Main
        Dim sr As IO.StreamReader
        Try
            sr = New IO.StreamReader("test.txt")
            Console.WriteLine(sr.ReadToEnd())
        Catch ex As IO.FileNotFoundException
            Console.WriteLine("FileNotFoundException")
        Catch ex As IO.IOException
            Console.WriteLine("IOException")
        Catch ex As Exception
            Console.WriteLine("Error Loading File")
        Finally
            sr.Close()
        End Try
   End Sub
End class
Hello world!

Create StreamReader from FileStream

Imports System.IO

Public Class Tester
    Public Shared Sub Main
        Dim f As System.IO.FileStream
        Dim r As System.IO.StreamReader
        Dim mylength As Integer
        Dim i As Integer
        f = New System.IO.FileStream("test.txt", IO.FileMode.Open, IO.FileAccess.Read)
        r = New System.IO.StreamReader(f)
        Console.WriteLine(r.ReadToEnd())
        f.Close()
        r.Close()
    End Sub
End Class

Read all text in a text file by using StreamReader

Imports System.IO
Module Module1
    Sub Main()
        Dim SourceFile As StreamReader
        Try
            SourceFile = New StreamReader("test.txt")
            Console.WriteLine(SourceFile.ReadToEnd())
            SourceFile.Close()
        Catch Except As Exception
            Console.WriteLine("Debug file does not yet exist")
        End Try
    End Sub
End Module
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...

Read text file to a char array

Imports System.IO

Public Class Tester
    Public Shared Sub Main
        Dim f As System.IO.FileStream
        Dim r As System.IO.StreamReader
        Dim mylength As Integer
        Dim i As Integer
        Dim mybuffer(100) As Char
        f = New System.IO.FileStream("test.txt", IO.FileMode.Open, IO.FileAccess.Read)
        r = New System.IO.StreamReader(f)
        r.Read(mybuffer, 0, 100)
        Console.WriteLine(mybuffer)
        f.Close()
        r.Close()
    End Sub
End Class

Read text file to the end

Imports System.IO
Public Class Tester
    Public Shared Sub Main
    
            Try
               Dim stream As StreamReader
               stream = New StreamReader("test.vb")
               Console.WriteLine(stream.ReadToEnd())
            Catch exceptionCatch As IOException
               Console.WriteLine("FILE ERROR")
            End Try
    End Sub
End Class

StreamReader: Peek

Imports System.IO
Public Class Tester
    Public Shared Sub Main
        Dim fsStream As New FileStream("test.txt", FileMode.Open, FileAccess.Read)
        Dim srReader As New StreamReader(fsStream)
        Try
            srReader.BaseStream.Seek(0, SeekOrigin.Begin)
            While srReader.Peek() > -1
                Console.WriteLine(srReader.ReadLine())
            End While
            srReader.Close()
        Catch ex As IOException
            Console.WriteLine(ex.Message)
        End Try
    End Sub
End Class

StreamReader: read to a buffer

Imports System.IO

Public Class Tester
    Public Shared Sub Main
        Dim f As System.IO.FileStream
        Dim r As System.IO.StreamReader
        Dim mylength As Integer
        Dim i As Integer
        Dim mybuffer(100) As Char
        f = New System.IO.FileStream("test.txt", IO.FileMode.Open, IO.FileAccess.Read)
        r = New System.IO.StreamReader(f)
        r.Read(mybuffer, 0, 100)
        Console.WriteLine(mybuffer)
        f.Close()
        r.Close()
    End Sub
End Class

Use Finally clause to close a stream

Imports System.IO
Imports System.Windows.Forms
Module Module1
    Sub Main()
        Dim FileDB As New OpenFileDialog()
        FileDB.Filter = "All files | *.* | Text files | *.txt"
        FileDB.FilterIndex = 2
        FileDB.InitialDirectory = "C:\Temp"
        FileDB.AddExtension = True
        FileDB.DefaultExt = "txt"
        If (FileDB.ShowDialog() = DialogResult.OK) Then
            Dim SourceFile As StreamReader
            SourceFile = New StreamReader(FileDB.FileName)
            If (Not SourceFile Is Nothing) Then
                Try
                    Console.WriteLine(SourceFile.ReadToEnd())
                Catch Except As Exception
                    Console.WriteLine("Error: " & Except.Message)
                Finally
                    Console.WriteLine("In finally statements")
                    SourceFile.Close()
                End Try
            End If
        Else
            Console.WriteLine("User selected Cancel")
        End If
    End Sub
End Module
Источник — «http://vbex.ru/index.php?title=VB.Net_Tutorial/Stream_File/StreamReader&oldid=3679»