FileInfo.Open Method (FileMode)


Opens a file in the specified mode.

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

Public Function Open (
	mode As FileMode
) As FileStream


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.

Exception Condition

The file is not found.


The file is read-only or is a directory.


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


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)
        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
    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.


for writing to and reading from files. Associated enumerations: FileIOPermissionAccess.Write and FileIOPermissionAccess.Read

Universal Windows Platform
Available since 10
.NET Framework
Available since 1.1
Available since 2.0
Windows Phone Silverlight
Available since 7.0
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