Vb.net read text files

Question

0.00/5 (No votes)

See more:

I want to write a program to read *.txt files in a certain folder. The new *.txt files creat all the time. How can I write the code to read new files and keep a high running efficiency.
I need a solution. Your input will be appreciated!

What I have tried:

I have no idea. When the program run a time, all the file will be read a time. The efficiency is to low.

Posted 20-Dec-17 1:10am

peterxuv

Updated 20-Dec-17 1:40am

Add a Solution

Comments

A_Griffin 20-Dec-17 7:28am

Use the FileSystemWatcher class to look for new files, and then read (only) those as they are created.

1 solution

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

OriginalGriff · Accepted Answer · 2017-12-20T01:40:00

Solution 1

As A_Griffin suggested, use a FileSystemWatcher[^] to monitor the folder.

Alternatively, keep a track of which files you have already processed, and only process ones which aren't on that list. (This method works better than a FileSystemWatcher if you app isn't running all the time). The list could be help in Text, JSON, XML, or even a DB - depends which is available and best for you.

Posted 20-Dec-17 1:40am

OriginalGriff

Comments

peterxuv 20-Dec-17 7:57am

Yes! The second solution should be the best one. But I hava a concerning while handreds of thousands of files in the folder, how can I make the app keeping a high efficiency when restart the app? If I track the name of files, should the app read all files again to check whether they are on the list? It's a waste of time.

OriginalGriff 20-Dec-17 8:17am

It won't take long: Windows caches folder contents, so it can return them quickly - and Linq has the Except method which will remove all those already there.

If you don't read all names, you don't know what is there! (And there is no GetFiles method which only returns files since a particular time, so you will need to do this every time you want to check for new items anyway unless you use a combination of list and FileSystemWatcher)

peterxuv 20-Dec-17 8:35am

OK, I will try it.
I wanted to read the file created time and record it in a text file. But PC date and time could be not right sometimes. So that it seems not strict.
@Griff, Thanks for your kindly help. ^_^

peterxuv 20-Dec-17 8:07am

Thank you! @Griff