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How to determine if a filename is valid?

Posted on 1997-09-02
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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. :-)
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Question by:wolfcrag
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4 Comments
 
LVL 8

Accepted Solution

by:
ZifNab earned 50 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;

begin
 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;
  inc(i);
 end;
end;
 
['\','/',':','?','"','<','>','|'] = 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;
0
 
LVL 3

Author Comment

by:wolfcrag
ID: 1343397
ZifNab,

    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.
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LVL 8

Expert Comment

by:ZifNab
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;
0
 
LVL 3

Author Comment

by:wolfcrag
ID: 1343399
ZifNab,

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