Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people, just like you, are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions

500pts: File Comparing a directory?

Posted on 2006-11-23
Last Modified: 2010-04-16
Hi there,

I wonder if anyone can help?

I am trying to find the easiest way to file compare a complete directory.. The reason for this is to find out if i need to send any changes in the directory to a Database BLOB field..

I have the blob field working... What i need to do is to take a Snapshot of all files when I enter my program... I thought of reading in the files into a array or something but a little unsure here...

During the use of the program files in a certain directroy may get updated or files maybe added or deleted.... so when i exit the program i will compare my previous Snapshot to the files now in the directory and if any have changed then i would send these files to the db.... or remove files from the db or add files to the db.....

Any help or info on this would be really helpful, i am a little lost the best way of doing this... If i keep the files in an array in memory this would be costly wouldn't it??

Thanks in advance

Question by:ianinspain
  • 3
  • 2
LVL 48

Assisted Solution

AlexFM earned 200 total points
ID: 18001775
Did you think about using FileSystemWatcher? Something like this:


Accepted Solution

redpipe earned 300 total points
ID: 18002772
The FileSystemWatcher is very good when you need to trigger on events, as they happen. If you only want to compare two different snapshots, I would used a simple hashtable.

    public System.Collections.Hashtable Init(string path)
      System.Collections.Hashtable ht = new System.Collections.Hashtable();
      System.IO.DirectoryInfo di = new System.IO.DirectoryInfo(path);
      foreach (System.IO.FileInfo fi in di.GetFiles()) {
        ht.Add(fi.Name, fi.LastWriteTime);

    public void Compare(string path, System.Collections.Hashtable htOld)
      System.Collections.Hashtable htCurrent = new System.Collections.Hashtable();
      System.IO.DirectoryInfo di = new System.IO.DirectoryInfo(path);
      foreach (System.IO.FileInfo fi in di.GetFiles()) {
        if (!htOld.ContainsKey(fi.Name)) {//new file
          //TODO: Add code to add current file to database
      foreach (System.Collections.DictionaryEntry de in htOld.Keys) {
        System.IO.FileInfo fi = new System.IO.FileInfo(path + "\\" + de.Key.ToString());
        if (fi.Exists) {
          if (fi.LastWriteTime > Convert.ToDateTime(de.Value)) {
            //TODO: Add code to update current file to database
        } else { //deleted file
          //TODO: Add code to remove current file from database

Author Comment

ID: 18003647
hi redpipe, this i like... but i was wondering about the property


is this guaranteed to be always updated when a feel is changed??

Just wondering, otherwise it sounds a really good solution..

AlexFM, this is also a brilliant solution, i will probably keep this and implement elsewhere.... i never even knew it existed... thnaks for that

Free Tool: ZipGrep

ZipGrep is a utility that can list and search zip (.war, .ear, .jar, etc) archives for text patterns, without the need to extract the archive's contents.

One of a set of tools we're offering as a way to say thank you for being a part of the community.


Author Comment

ID: 18004016
feel is supposed to read "file" :-)


Expert Comment

ID: 18006289
hi Ian

The "LastWriteTime" property is the same as the "Date Modified" column in Windows Explorer. As all properties with a getter and setter it is possible to programatically override the "correct" value (e.g. set the LastWriteTime to a date before the computer was invented :-), but if you just write your changes to the file through the normal System.IO methods, the property should be updated accordingly by the OS.

Author Comment

ID: 18029609
Thank you...

Much appreciated


Featured Post

Free Tool: Postgres Monitoring System

A PHP and Perl based system to collect and display usage statistics from PostgreSQL databases.

One of a set of tools we are providing to everyone as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

This article is for Object-Oriented Programming (OOP) beginners. An Interface contains declarations of events, indexers, methods and/or properties. Any class which implements the Interface should provide the concrete implementation for each Inter…
It was really hard time for me to get the understanding of Delegates in C#. I went through many websites and articles but I found them very clumsy. After going through those sites, I noted down the points in a easy way so here I am sharing that unde…
Established in 1997, Technology Architects has become one of the most reputable technology solutions companies in the country. TA have been providing businesses with cost effective state-of-the-art solutions and unparalleled service that is designed…
The Email Laundry PDF encryption service allows companies to send confidential encrypted  emails to anybody. The PDF document can also contain attachments that are embedded in the encrypted PDF. The password is randomly generated by The Email Laundr…

792 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question