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File.SetLastWriteTime Method

Sets the date and time that the specified file was last written to.

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

public static void SetLastWriteTime (
	string path,
	DateTime lastWriteTime
)
public static void SetLastWriteTime (
	String path, 
	DateTime lastWriteTime
)
public static function SetLastWriteTime (
	path : String, 
	lastWriteTime : DateTime
)

Parameters

path

The file for which to set the date and time information.

lastWriteTime

A DateTime containing the value to set for the last write date and time of path. This value is expressed in local time.

Exception typeCondition

ArgumentException

path is a zero-length string, contains only white space, or contains one or more invalid characters as defined by InvalidPathChars.

ArgumentNullException

path is a null reference (Nothing in Visual Basic).

PathTooLongException

The specified path, file name, or both exceed the system-defined maximum length. For example, on Windows-based platforms, paths must be less than 248 characters, and file names must be less than 260 characters.

FileNotFoundException

The specified path was not found.

UnauthorizedAccessException

The caller does not have the required permission.

NotSupportedException

path is in an invalid format.

ArgumentOutOfRangeException

lastWriteTime specifies a value outside the range of dates or times permitted for this operation.

The path parameter is permitted to specify relative or absolute path information. Relative path information is interpreted as relative to the current working directory. To obtain the current working directory, see GetCurrentDirectory.

For an example of using this method, see the Example section. 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

The following example checks the file system for the specified file, creating the file if necessary, and then sets and gets the last write time of the file.

using System;
using System.IO;

class Test 
{
    public static void Main() 
    {
        try 
        {
            string path = @"c:\Temp\MyTest.txt";
            if (!File.Exists(path)) 
            {
                File.Create(path);
            } 
            else 
            {
                // Take an action that will affect the write time.
                File.SetLastWriteTime(path, new DateTime(1985,4,3));
            }

            // Get the creation time of a well-known directory.
            DateTime dt = File.GetLastWriteTime(path);
            Console.WriteLine("The last write time for this file was {0}.", dt);
			
            // Update the last write time.
            File.SetLastWriteTime(path, DateTime.Now);
            dt = File.GetLastWriteTime(path);
            Console.WriteLine("The last write time for this file was {0}.", dt);

        } 
        catch (Exception e) 
        {
            Console.WriteLine("The process failed: {0}", e.ToString());
        }
    }
}

import System.*;
import System.IO.*;

class Test
{
    public static void main(String[] args)
    {
        try {
            String path = "c:\\Temp\\MyTest.txt";
            if (!(File.Exists(path))) {
                File.Create(path);
            }
            else {
                // Take an action that will affect the write time.
                File.SetLastWriteTime(path, new DateTime(1985, 4, 3));
            }

            // Get the creation time of a well-known directory.
            DateTime dt = File.GetLastWriteTime(path);
            Console.WriteLine("The last write time for this file was {0}.",
                dt);

            // Update the last write time.
            File.SetLastWriteTime(path, DateTime.get_Now());
            dt = File.GetLastWriteTime(path);
            Console.WriteLine("The last write time for this file was {0}.",
                dt);
        }
        catch (System.Exception e) {
            Console.WriteLine("The process failed: {0}", e.ToString());
        }
    } //main
} //Test

Windows 98, Windows 2000 SP4, Windows Millennium Edition, 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

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