FileSystemInfo.LastWriteTime Property

 
System_CAPS_noteNote

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Gets or sets the time when the current file or directory was last written to.

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

Public Property LastWriteTime As Date

Property Value

Type: System.DateTime

The time the current file was last written.

Exception Condition
IOException

Refresh cannot initialize the data.

PlatformNotSupportedException

The current operating system is not Windows NT or later.

ArgumentOutOfRangeException

The caller attempts to set an invalid write time.

Note   This method may return an inaccurate value, because it uses native functions whose values may not be continuously updated by the operating system.

The value of the LastWriteTime property is pre-cached if the current instance of the FileSystemInfo object was returned from any of the following DirectoryInfo methods:

To get the latest value, call the Refresh method.

If the file described in the FileSystemInfo object does not exist, this property will return 12:00 midnight, January 1, 1601 A.D. (C.E.) Coordinated Universal Time (UTC), adjusted to local time.

This property value is null if the file system containing the file does not support this information.

Win95Win98Win98Se

These operating systems do not support this property, and DirectoryInfo implementations of this property are not supported.

The following code example demonstrates the updating of the LastWriteTime property through a "touch" operation. In this example, the file is "touched", updating the CreationTime, LastAccessTime and LastWriteTime properties to the current date and time.

Imports System
Imports System.IO

Public Class Touch
    Public Shared Sub Main(ByVal args() As String)

        ' Make sure an argument (filename) was provided.
        If args.Length > 0 Then

            ' Verify that the provided filename exists.
            If File.Exists(args(0)) Then
                Dim fi As FileInfo = New FileInfo(args(0))
                touchFile(fi)
            Else
                Console.WriteLine("Could not find the file {0}", args(0))
            End If
        Else
            Console.WriteLine("No file specified.")
        End If
    End Sub

    Public Shared Sub touchFile(ByVal fsi As FileSystemInfo)
        Console.WriteLine("Touching: {0}", fsi.FullName)

        ' Update the CreationTime, LastWriteTime and LastAccessTime.
        Try
            fsi.CreationTime = DateTime.Now
            fsi.LastAccessTime = DateTime.Now
            fsi.LastWriteTime = DateTime.Now
        Catch e As Exception
            Console.WriteLine("Error: {0}", e.Message)
        End Try

    End Sub

End Class

FileIOPermission

for setting the last write time. Associated enumeration: FileIOPermissionAccess.Write

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