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FileSystemInfo.LastWriteTime Property

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

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

public DateTime LastWriteTime { get; set; }
/** @property */
public DateTime get_LastWriteTime ()

/** @property */
public void set_LastWriteTime (DateTime value)

public function get LastWriteTime () : DateTime

public function set LastWriteTime (value : DateTime)

Property Value

The time the current file was last written.

Exception typeCondition

IOException

Refresh cannot initialize the data.

PlatformNotSupportedException

The current operating system is not Microsoft Windows NT or later.

When first called, FileSystemInfo calls Refresh and returns the cached information on APIs to get attributes and so on. On subsequent calls, you must call Refresh to get the latest copy of the information.

This property value is a null reference (Nothing in Visual Basic) if the file system containing the file does not support this information.

The following table lists examples of other typical or related I/O tasks.

To do this...

See the example in this topic...

Write to a text file.

How to: Write Text to a File

Read from a text file.

How to: Read Text from a File

Append text to a file.

How to: Open and Append to a Log File

File.AppendText

FileInfo.AppendText

Rename or move a file.

File.Move

FileInfo.MoveTo

Get the attributes of a file.

File.GetAttributes

Set the attributes of a file.

File.SetAttributes

Windows 95, Windows 98, Windows 98 Second Edition Platform Note: These operating systems do not support this property, and DirectoryInfo implementations of this property are not supported.

Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows CE Platform Note: This property is read-only.

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.

using System;
using System.IO;

namespace touch
{
    class Touch
    {
        static void Main(string[] args)
        {
            // Make sure a filename was provided.
            if (args.Length > 0)
            {
                // Verify that the provided filename exists.
                if (File.Exists(args[0]))
                {
                    FileInfo fi = new FileInfo(args[0]);
                    touchFile(fi);
                }
                else
                {
                    Console.WriteLine(
                        "Could not find the file: {0}.", args[0]);
                }
            }
            else
            {
                Console.WriteLine("No file was specified.");
            }
        }

        static void touchFile(FileSystemInfo fsi)
        {
            Console.WriteLine("Touching: {0}", fsi.FullName);

            // Update the CreationTime, LastWriteTime and LastAccessTime.
            try
            {
                fsi.CreationTime = fsi.LastWriteTime = fsi.LastAccessTime =
                    DateTime.Now;
            }
            catch (Exception e)
            {
                Console.WriteLine("Error: {0}", e.Message);
            }
        }
    }
}

Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

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

.NET Framework

Supported in: 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0, 1.0

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