FileMode Enumeration

July 28, 2014

Specifies how the operating system should open a file.

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

'Declaration
Public Enumeration FileMode

Member nameDescription
AppendOpens the file if it exists and seeks to the end of the file, or creates a new file. Append can only be used in conjunction with Write. Attempting to seek to a position before the end of the file will throw an IOException and any attempt to read fails and throws an NotSupportedException.
CreateSpecifies that the operating system should create a new file. If the file already exists, it will be overwritten. Create is equivalent to requesting that if the file does not exist, use CreateNew; otherwise, use Truncate.
CreateNewSpecifies that the operating system should create a new file.
OpenSpecifies that the operating system should open an existing file. The ability to open the file is dependent on the value specified by FileAccess. A System.IO.FileNotFoundException is thrown if the file does not exist.
OpenOrCreateSpecifies that the operating system should open a file if it exists; otherwise, a new file should be created.
TruncateSpecifies that the operating system should open an existing file. Once opened, the file should be truncated so that its size is zero bytes.

Specify a FileMode parameter IsolatedStorageFileStream constructors.

FileMode parameters control whether a file is overwritten, created, opened, or some combination thereof. Use Open to open an existing file. To append to a file, use Append. To truncate a file or create a file if it doesn't exist, use Create.

The following example opens an existing file. This example is part of a larger example provided for the IsolatedStorageFile class.


' Write to an existing file: MyApp1\SubDir1\MyApp1A.txt

' Determine if the file exists before writing to it.
Dim filePath As String = Path.Combine(subdirectory1, "MyApp1A.txt")

If store.FileExists(filePath) Then
    Try
        Using sw As StreamWriter = _
            New StreamWriter(store.OpenFile(filePath, FileMode.Open, FileAccess.Write))

            sw.WriteLine("To do list:")
            sw.WriteLine("1. Buy supplies.")
        End Using

    Catch ex As IsolatedStorageException
        sb.AppendLine(ex.Message)
    End Try
Else
    sb.AppendLine((filePath + "does not exist"))
End If


Windows Phone OS

Supported in: 8.1, 8.0, 7.1, 7.0

Windows Phone

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