How to find the most recent file in a directory using NET and without looping

Question

I need to find the most recently modified file in a directory    I know I can loop through every file in a folder and compare File GetLastWriteTime  but is there a better way to do this without looping

User · Answer

Here s a version that gets the most recent file from each subdirectory  List lt string gt  reports   new List lt string gt         DirectoryInfo directory   new DirectoryInfo ReportsRoot   directory GetFiles    xlsx   SearchOption AllDirectories  GroupBy fl   gt  fl DirectoryName   ForEach g   gt  reports Add g OrderByDescending fi   gt  fi LastWriteTime  First   FullName

User · Answer

it s a bit late but     your code will not work  because of list lt FileInfo gt  lastUpdateFile   null  and later lastUpdatedFile Add file   so NullReference exception will be thrown  Working version should be   private List lt FileInfo gt  GetLastUpdatedFileInDirectory DirectoryInfo directoryInfo        FileInfo   files   directoryInfo GetFiles        List lt FileInfo gt  lastUpdatedFile   new List lt FileInfo gt         DateTime lastUpdate   DateTime MinValue      foreach  FileInfo file in files                if  file LastAccessTime  gt  lastUpdate                        lastUpdatedFile Add file               lastUpdate   file LastAccessTime                       return lastUpdatedFile      Thanks

User · Answer

Short and simple   new DirectoryInfo path  GetFiles   OrderByDescending o   gt  o LastWriteTime  FirstOrDefault

User · Answer

A non-LINQ version        lt summary gt      Returns latest writen file from the specified directory      If the directory does not exist or doesn t contain any file  DateTime MinValue is returned       lt  summary gt       lt param name  directoryInfo  gt Path of the directory that needs to be scanned lt  param gt       lt returns gt  lt  returns gt  private static DateTime GetLatestWriteTimeFromFileInDirectory DirectoryInfo directoryInfo        if  directoryInfo    null     directoryInfo Exists          return DateTime MinValue       FileInfo   files   directoryInfo GetFiles        DateTime lastWrite   DateTime MinValue       foreach  FileInfo file in files                if  file LastWriteTime  gt  lastWrite                        lastWrite   file LastWriteTime                       return lastWrite          lt summary gt      Returns file s latest writen timestamp from the specified directory      If the directory does not exist or doesn t contain any file  null is returned       lt  summary gt       lt param name  directoryInfo  gt Path of the directory that needs to be scanned lt  param gt       lt returns gt  lt  returns gt  private static FileInfo GetLatestWritenFileFileInDirectory DirectoryInfo directoryInfo        if  directoryInfo    null     directoryInfo Exists          return null       FileInfo   files   directoryInfo GetFiles        DateTime lastWrite   DateTime MinValue      FileInfo lastWritenFile   null       foreach  FileInfo file in files                if  file LastWriteTime  gt  lastWrite                        lastWrite   file LastWriteTime              lastWritenFile   file                      return lastWritenFile

User · Answer

Expanding on the first one above  if you want to search for a certain pattern you may use the following code    string pattern      txt   var dirInfo   new DirectoryInfo directory   var file    from f in dirInfo GetFiles pattern  orderby f LastWriteTime descending select f  First

User · Answer

private List lt FileInfo gt  GetLastUpdatedFileInDirectory DirectoryInfo directoryInfo        FileInfo   files   directoryInfo GetFiles        List lt FileInfo gt  lastUpdatedFile   null      DateTime lastUpdate   new DateTime 1  0  0       foreach  FileInfo file in files                if  file LastAccessTime  gt  lastUpdate                        lastUpdatedFile Add file               lastUpdate   file LastAccessTime                       return lastUpdatedFile

User · Answer

If you want to search recursively  you can use this beautiful piece of code   public static FileInfo GetNewestFile DirectoryInfo directory       return directory GetFiles           Union directory GetDirectories   Select d   gt  GetNewestFile d            OrderByDescending f   gt   f    null   DateTime MinValue   f LastWriteTime           FirstOrDefault                                Just call it the following way   FileInfo newestFile   GetNewestFile new DirectoryInfo   C  directory        and that s it  Returns a FileInfo instance or null if the directory is empty

User · Answer

I do this is a bunch of my apps and I use a statement like this     var inputDirectory   new DirectoryInfo    Directory Path here      var myFile   inputDirectory GetFiles   OrderByDescending f   gt  f LastWriteTime  First      From here you will have the filename for the most recently saved added updated file in the Directory of the  inputDirectory  variable  Now you can access it and do what you want with it   Hope that helps

User · Answer

Another approach if you are using Directory EnumerateFiles and want to read files in latest modified by first   foreach  string file in Directory EnumerateFiles fileDirectory  fileType  OrderByDescending f   gt  new FileInfo f  LastWriteTime

User · Answer

how about something like this     var directory   new DirectoryInfo  C   MyDirectory    var myFile    from f in directory GetFiles                orderby f LastWriteTime descending              select f  First        or    var myFile   directory GetFiles                 OrderByDescending f   gt  f LastWriteTime                First

User · Answer

You can react to new file activity with FileSystemWatcher

[c#] How to find the most recent file in a directory using .NET, and without looping?

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