Redigera

Dela via

FileSystemInfo.LastWriteTime Property

  • Reference

Definition

Namespace:
System.IO
Assemblies:
mscorlib.dll, System.IO.FileSystem.dll
Assembly:
System.IO.FileSystem.dll
Assembly:
System.Runtime.dll
Assembly:
mscorlib.dll
Assembly:
netstandard.dll
Source:
FileSystemInfo.cs
Source:
FileSystemInfo.cs
Source:
FileSystemInfo.cs

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

public:
 property DateTime LastWriteTime { DateTime get(); void set(DateTime value); };
public DateTime LastWriteTime { get; set; }
member this.LastWriteTime : DateTime with get, set
Public Property LastWriteTime As DateTime

Property Value

DateTime

The time the current file was last written.

Exceptions

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.

Examples

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);
            }
        }
    }
}

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

Remarks

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 or directory described in the FileSystemInfo object does not exist, or if the file system that contains this file or directory does not support this information, this property returns 12:00 midnight, January 1, 1601 A.D. (C.E.) Coordinated Universal Time (UTC), adjusted to local time.

Applies to

See also