How to determine if a filename is valid?

Posted on 1997-09-02
Last Modified: 2010-04-04
Hi, how do I determine if a string entered by the user is a valid filename? Forget the extension part (.*), just the first part, because I'll set the extension myself. The user just has to give the first part.

Yes, this is for Win95. I use Delphi3. I know of one way already, but it relies on an error being generated, and I would prefer a neater (maybe safer?) way.

If the answer you give me does not require trapping an error, and is correct, I'll give you an A. If it does require error trapping, and it's correct, I'll give you a C. If it's wrong, well, it's wrong. :-)
Question by:wolfcrag
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
  • 2
  • 2

Accepted Solution

ZifNab earned 25 total points
ID: 1343396
Hi wolfcrag,

Don't know if this is such a good solution, but it is one :

{function returns true if filename is correct}

function CheckFileName(Value:TFileName):Boolean;
var i : integer;

 Result := True;
 i := 0;

 { iterate through filename [Value] until : }
 {  Bad character : return false            }
 {  Or checked all characters : return true }

 while result and (i<>length(Value)) do begin
  if Value[i] in ['\','/',':','?','"','<','>','|'] then
   result := false;
['\','/',':','?','"','<','>','|'] = characters which may not be for a filename. Possibly you should add '.', because you give the extension yourself.
Hope I've helped you with this,
Have fun,
c.u. ZifNab;

Author Comment

ID: 1343397

    I'm giving you a B. Why? Well, you missed one: '*' I've decided that I will use your method but will protect it with the error trapping method. Thanks for your help.

Expert Comment

ID: 1343398
Hi wolfcrag,

Well, you're correct, sorry I've missed that '*'. But I'm not really doing it for the points, I just want to help people.

Have fun,
c.u. ZifNab;

Author Comment

ID: 1343399

   That's a rare attribute you have there, ZifNab. Well, not so rare for a Delphi user. ;-)

Featured Post

Free Tool: SSL Checker

Scans your site and returns information about your SSL implementation and certificate. Helpful for debugging and validating your SSL configuration.

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

Have you ever had your Delphi form/application just hanging while waiting for data to load? This is the article to read if you want to learn some things about adding threads for data loading in the background. First, I'll setup a general applica…
Introduction I have seen many questions in this Delphi topic area where queries in threads are needed or suggested. I know bumped into a similar need. This article will address some of the concepts when dealing with a multithreaded delphi database…
Exchange organizations may use the Journaling Agent of the Transport Service to archive messages going through Exchange. However, if the Transport Service is integrated with some email content management application (such as an antispam), the admini…
Attackers love to prey on accounts that have privileges. Reducing privileged accounts and protecting privileged accounts therefore is paramount. Users, groups, and service accounts need to be protected to help protect the entire Active Directory …

726 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