C# Program to get the last write time of a file

To get the last write time of a file in C#, you can use the LastWriteTime property of the FileInfo class. This property returns a DateTime object representing when the file was last modified.

You can also use the static File.GetLastWriteTime() method as an alternative approach for retrieving the last write time without creating a FileInfo instance.

Syntax

Using FileInfo class −

FileInfo fileInfo = new FileInfo("filename.txt");
DateTime lastWrite = fileInfo.LastWriteTime;

Using File.GetLastWriteTime() method −

DateTime lastWrite = File.GetLastWriteTime("filename.txt");

Using FileInfo Class

The FileInfo class provides comprehensive file information including creation time, last access time, and last write time −

using System;
using System.IO;

public class Program {
    public static void Main() {
        using (StreamWriter sw = new StreamWriter("sample.txt")) {
            sw.WriteLine("This is a sample file.");
            sw.WriteLine("Last write time will be recorded.");
        }
        
        FileInfo file = new FileInfo("sample.txt");
        
        // file creation time
        DateTime creationTime = file.CreationTime;
        Console.WriteLine("Creation Time: " + creationTime);
        
        // last access time
        DateTime lastAccessTime = file.LastAccessTime;
        Console.WriteLine("Last Access Time: " + lastAccessTime);
        
        // last write time
        DateTime lastWriteTime = file.LastWriteTime;
        Console.WriteLine("Last Write Time: " + lastWriteTime);
    }
}

The output of the above code is −

Creation Time: 12/15/2023 3:45:22 PM
Last Access Time: 12/15/2023 3:45:22 PM
Last Write Time: 12/15/2023 3:45:22 PM

Using File.GetLastWriteTime() Method

For a simpler approach when you only need the last write time, use the static File.GetLastWriteTime() method −

using System;
using System.IO;

public class Program {
    public static void Main() {
        // Create a sample file
        File.WriteAllText("example.txt", "Sample content for demonstration.");
        
        // Get last write time using File.GetLastWriteTime()
        DateTime lastWrite = File.GetLastWriteTime("example.txt");
        Console.WriteLine("Last Write Time: " + lastWrite);
        
        // Modify the file
        System.Threading.Thread.Sleep(2000); // Wait 2 seconds
        File.AppendAllText("example.txt", "\nAdditional content added.");
        
        // Check the updated last write time
        DateTime updatedLastWrite = File.GetLastWriteTime("example.txt");
        Console.WriteLine("Updated Last Write Time: " + updatedLastWrite);
    }
}

The output of the above code is −

Last Write Time: 12/15/2023 3:45:25 PM
Updated Last Write Time: 12/15/2023 3:45:27 PM

Comparison

Conclusion

Getting the last write time of a file in C# is straightforward using either FileInfo.LastWriteTime property or File.GetLastWriteTime() method. Choose FileInfo when you need multiple file properties, or use the static File method for simple, one-time queries.