How to retrieve list of files in directory, sorted by name

58,869

Solution 1

var files = Directory.EnumerateFiles(folder)
                     .OrderByDescending(filename => filename);

(The EnumerateFiles method is new in .NET 4, you can still use GetFiles if you're using an earlier version)


EDIT: actually you don't need to sort the file names, if you use the MaxBy method defined in MoreLinq:

var lastFile = Directory.EnumerateFiles(folder).MaxBy(filename => filename);

Solution 2

var files = from file in Directory.GetFiles(folder)    
               orderby file descending 
               select file;

var biggest = files.First();

if you are really after the highest number and those logfiles are named like you suggested, how about:

Directory.GetFiles(folder).Length

Solution 3

Extending what @Thomas said, if you only need the top X files, you can do this:

int x = 10;
var files = Directory.EnumerateFiles(folder)
                 .OrderByDescending(filename => filename)
                 .Take(x);
Share:
58,869
BerggreenDK
Author by

BerggreenDK

Started programming as very young on a Commodore VIC-20 and 64. First in BASIC, then moved to 8-bit assembler/machinecode to make things run more smooth. Ended up building a game for it with two friends which we sold and earned Amiga 500 computers. This lead me to the assembler of Motorola 680x0 series CPU. Great CPU btw. Took an IT-education, learned C/C++ and used some Pascal. Build my first networking application for the school I was on, as we needed a cross location chat-tool in DOS. Made it upon Netware/IPX protocol. Then I went and became in love with C++ and its possiblities. Got brainwashed at school, came out saying: Windows, Windows, Windows... so I started to look at DirectX for direct computer power, usable for further multimedia/game development. I've composed a some computer-music too, back in the old C64 days, but thats another story. Later on, I got employed in different companies, including IT-consulting and support. Then worked with advertising/commercial companies as "Multimedia architect/systemdeveloper". I've been all the way through the different browserplatforms and "wars", been building cross platform websites with dynamic HTML from the very early days with Netscape LAYER tags and MSIE DIV, makeing sure that things ALSO worked on Macintosh platoform, so cross platform development has been my goal since 1997. I design and implement SQL-server structures too, so the backend is ready for the frontend. Today I run my own small company, working mostly with .NET and C#, but XHTML/CSS/XML/JQUERY + some Flash Actionscript 3.0 is also part of my work from time to time. Overall - the company is focusing on making the internet easier to learn and use, therefore somethings might be hard to develop, but as long as it will help the user to get respons/results faster and easier, we still go for the "hard way" of developing stuff. Better think before errors happends. I dont have a "language" religion, I dont care what platform we use, as long as its the best for the purpose and we dont have to pay gazillions for licenses. I dont mind paying for quality, but dang - there is really a lot of wanna-be crap out there, so I do check upon things before investing time and money. And no, I dont go for the easy way. I go for the most valueable way, for the customer.

Updated on July 09, 2022

Comments

  • BerggreenDK
    BerggreenDK almost 2 years

    I am trying to get a list of all files in a folder from C#. Easy enough:

    Directory.GetFiles(folder)
    

    But I need the result sorted alphabetically-reversed, as they are all numbers and I need to know the highest number in the directory. Of course I could grab them into an array/list object and then do a sort, but I was wondering if there is some filter/parameter instead?

    They are all named with leading zeros. Like:

    00000000001.log
    00000000002.log
    00000000003.log
    00000000004.log
    ..
    00000463245.log
    00000853221.log
    00024323767.log
    

    Whats the easiest way? I dont need to get the other files, just the "biggest/latest" number.

  • Matías Fidemraizer
    Matías Fidemraizer almost 13 years
    And a ".ToList()" would be perfect :D
  • BerggreenDK
    BerggreenDK almost 13 years
    okay, this looks like LINQ syntax, as from what I understand it still pulls the whole directory into memory before selecting? I am searching for a "filter" on the Directory command itself, as we might have quite a load of files in same directory and this function will be called a lot.
  • Thomas Levesque
    Thomas Levesque almost 13 years
    @Matías Fidemraizer, why? It depends on what you intend to do with the results...
  • BerggreenDK
    BerggreenDK almost 13 years
    Interesting with .NET4 (we run 3.5 I think), but same problem as @yas4891 I guess? every filename is pulled into memory before the LINQ syntax selects the correct item. I am looking for a simple parametre for the Directory object? is that possible?
  • yas4891
    yas4891 almost 13 years
    Hmm. How about you clarify your post a bit more and tell us what you ultimately want to achieve? It seems like you are trying to "guess" the next valid integer in some naming scheme - right?
  • Matías Fidemraizer
    Matías Fidemraizer almost 13 years
    @Thomas Because you know this works with deferred execution and since this is a sample and maybe question's author isn't a LINQ expert, it seems that this should avoid problems for him.
  • BerggreenDK
    BerggreenDK almost 13 years
    I want to know the name of the file with the highest number, either for appending more logs or to be able to produce the next number in line. So yes, "guessing the next" is one of the tasks. I dont need the list of all the others as my question also states.
  • Matías Fidemraizer
    Matías Fidemraizer almost 13 years
    @BerggreenDK Directory.GetFiles returns an array of strings (file names) so you're not iterating "files".
  • Thomas Levesque
    Thomas Levesque almost 13 years
    @BerggreenDK, no, there is no parameter for Directory.GetFiles to specify the order. EnumerateFiles yields the file names lazily, so they're not all loaded in memory at once. However, the OrderBy will need to load everything before it can begin to sort... Instead you could use the MaxBy method defined in MoreLinq. See my updated answer
  • yas4891
    yas4891 almost 13 years
    If performance is really that big a matter (did you benchmark ?), you maybe should resolve to storing the highest number somewhere in memory (i.e. a class member / property)
  • BerggreenDK
    BerggreenDK almost 13 years
    Yes, that could be another option. But my question is just: IS THERE a parameter in .NET that does the filtering automatically or isnt it possible to get the reverse order of files.
  • BerggreenDK
    BerggreenDK almost 13 years
    I have tried it now, but got an error when the folder was empty. Guess its something with the First() command, so I used the Length to check if there is files at all before firing the LINQ
  • BerggreenDK
    BerggreenDK almost 13 years
    Yup! decided to listen to the community here. IF there is a performance issue, deal with it WHEN and IF it happens... ever! Buy a larger server/harddrive/controller. LOL!
  • BerggreenDK
    BerggreenDK about 11 years
    Okay thanks for great answers and comments everyone! Just had to get this confirmed.
  • BerggreenDK
    BerggreenDK over 7 years
    Thanks! That can be really helpful too.
  • userAZLogicApps
    userAZLogicApps almost 6 years
    i wanted to get each file from the folder/directory.my file name contains some ID _documentt_filename.docx , kind of .Now, i wanna split this file title with ID and store it in a table or in-memory. how to achieve this ?
  • userAZLogicApps
    userAZLogicApps almost 6 years
    var dir = new DirectoryInfo(@"D:\folder1"); foreach (var singleFile in dir.EnumerateFiles(".", SearchOption.AllDirectories)) { if(singleFile != null && singleFile.Length > 0 ) {