FileInfo.Open Method (FileMode)

Opens a file in the specified mode.

Namespace:  System.IO
Assembly:  mscorlib (in mscorlib.dll)

'Declaration
Public Function Open ( _
	mode As FileMode _
) As FileStream

Parameters

mode
Type: System.IO.FileMode

A FileMode constant specifying the mode (for example, Open or Append) in which to open the file.

Return Value

Type: System.IO.FileStream
A file opened in the specified mode, with read/write access and unshared.

ExceptionCondition
FileNotFoundException

The file is not found.

UnauthorizedAccessException

The file is read-only or is a directory.

DirectoryNotFoundException

The specified path is invalid, such as being on an unmapped drive.

IOException

The file is already open.

The following example opens a file, adds some information to the file, and reads the file.

Imports System
Imports System.IO
Imports System.Text

Public Class Test

    Public Shared Sub Main()
        Dim path As String = "c:\temp\MyTest.txt" 
        Dim fi As FileInfo = New FileInfo(path)
        Dim fs As FileStream

        ' Delete the file if it exists. 
        If fi.Exists = False Then 
            'Create the file.
            fs = fi.Create()
            Dim info As Byte() = New UTF8Encoding(True).GetBytes("This is some text in the file.")
            'Add some information to the file.
            fs.Write(info, 0, info.Length)
            fs.Close()
        End If 

        'Open the stream and read it back.
        fs = fi.Open(FileMode.Open)
        Dim b(1024) As Byte 
        Dim temp As UTF8Encoding = New UTF8Encoding(True)
        Do While fs.Read(b, 0, b.Length) > 0
            Console.WriteLine(temp.GetString(b))
        Loop
        fs.Close()
    End Sub 
End Class 
'This code produces output similar to the following;  
'results may vary based on the computer/file structure/etc.: 

'This is some text in the file. 











'

.NET Framework

Supported in: 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone Silverlight 8.1, Windows Phone Silverlight 8

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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