The last file inside the last folder

When I come across a coding "challenge" like this, I'm always looking to see ... assuming I think I'll be using similar code for similar purposes in the future ... if I can create a small "tool", and, in fact, I have written code for this task in the past.

Here's a "sketch" of how, given a valid Directory-path you can find the last, or first, file created, or modified (last written-to). I omit code to find the last (or first) Directory, since that's so easy to do, and I think you already know how to do that.

This "incomplete sketch" will compile, and get you the first created or modified file in a Directory. You can have the challenge/pleasure of extending it to return last created, or modified:

// in NameSpace scope
public enum GetDateBy
{
    FirstCreated,
    LastCreated,
    FirstModified,
    LastModified
}

// in some Class' scope
private const string SearchAllString = ".";

public FileInfo GetFileDateBy(string directoryPath, bool recursive, GetDateBy datebyType)
{
    if(! Directory.Exists(directoryPath)) throw new ArgumentException("invalid directory path");

    var files = new DirectoryInfo(directoryPath).EnumerateFiles(
        SearchAllString,
        (recursive)
            ? SearchOption.AllDirectories
            : SearchOption.TopDirectoryOnly
        );

    if (files.Count() == 0) return null;

    switch (datebyType)
    {
        case GetDateBy.FirstCreated:
            return files.OrderBy(f => f.CreationTime).First();
        case GetDateBy.LastCreated:
            // for you to write
            break; // break is here so this will compile and run
        case GetDateBy.FirstModified:
            return files.OrderBy(f => f.LastWriteTime).First();
        case GetDateBy.LastModified:
            // for you to write
            break; // break is here so this will compile and run
    }

    // throw error ?
    return null;
}

A test of this code ... assume you have a TextBox named 'textBox1 on a Form with its 'MultiLine property set to 'true:

private string format = "'Date:'MM/dd/yyyy\r\n'Time: 'H:mm:ss 'milliseconds:  ' FFFFFFF\r\n'UTC:  ' zzz";

string filepath = @"C:\Users\YourUserName\Desktop\SomeOuterFolder\SomeInnerFolder";

var f1 = GetFileDateBy(filepath, false, GetDateBy.FirstCreated);
if (f1 != null) 
{
    f1.Refresh();
    textBox1.AppendText(string.Format("file first created: {0}\r\n{1}\r\n\r\n",f1.Name,f1.CreationTime.ToString(format)));
}

var f3 = GetFileDateBy(filepath, false, GetDateBy.FirstModified);
if (f3 != null)
{
    f3.Refresh();
    textBox1.AppendText(string.Format("file first modified\r\n{0}\r\n{1}\r\n\r\n",f3.Name,f3.LastWriteTime.ToString(format)));
}

// you should see output like this in the TextBox:

//file first created: SomeFileName.txt
//Date:09/22/2014
//Time: 22:18:17 milliseconds:   2414408
//UTC:   +07:00

Note:

a. why use an Enum here ? I just plain like Enums, and feel they make code more readable/maintainable/expressive-of-intent, and, many times, easier to extend.

b. this method returns a FileInfo ... or ... null

c. re use of 'EnumerateFiles rather than 'GetFiles: 'EnumerateFiles may be more efficient in some cases. There's a very good CodeProject article that explores/documents this: [^].

d. you could re-write this as a static extension method, easily.

e. wonder why the LastAccessTime.Millisecond vale is some odd value, or #0: well, so do other people: [^].

f. note the use of the 'Refresh method on the FileInfo instance here: this is to ensure the file system manager has refreshed FileInfo instances it has cached: [^].

I found it !!!!!

string[] folders = Directory.GetDirectories(@"C:\\xxx\\", "*", SearchOption.AllDirectories);
            var directory = Directory.GetDirectories(@"C:\\xxx\\", "*", SearchOption.AllDirectories).OrderByDescending(d => new DirectoryInfo(d).CreationTime).Select(Path.GetFileNameWithoutExtension);
            var file = Directory.GetFiles(@"C:\\xxx\\", "*", SearchOption.AllDirectories).OrderByDescending(d => new FileInfo(d).CreationTime).Select(Path.GetFileNameWithoutExtension);
            var selector = from i in file
                           orderby new FileInfo(i).CreationTime descending
                           select i;
            var last = selector.FirstOrDefault();
            textBox2.Text = last;