Hi All,
I am using Regular Expressions in VB.NET to find illegal filename characters in a string. The user enters and name, and it then saves the file with that name. I just need to make sure that the filename doesn't contain illegal filename characters.

The characters are / \ : ? " < > | (is there any others?)

I am using the following regex at the moment, but it doesn't seem to be picking up backslashes.


Every other character it picks up, why just this one? Also the " character is illegal, how can i put that into the regex (at the moment it thinks its part of the code and not the regex)

If there is another way to do the same thing, or a different regex, that would be nice!

Thanks,
-jimmy

Have you tried escaping the \ with another \ - therefore making a \\ out of it?
The same trick might work by putting a \" instead of the "
The backslash is a good guess for what the escape character is in many environments, it might be that in VB.NET it's the same as well.

This post has been edited by dserban: Feb 20 2008, 07:27 AM

For " you need to escape with " itself.

And of course you probably need to protect \ from itself (usually \ means "ignore what follows me"). So, instead of \ you should write down \\.
I have this problem with the character $ in my script, I have to protect it, so instead of $ I write down \$.
So, amongs things not to be used in a filename, I think that you should add the following ones :
. (the dot, ".")
+ (because on Unix systems a+b will try to calculate the sum of a and b )
- (same reason, substracting)
=(a=b will be evaluated as "does the variable a be equal to the variable b" or a syntax error)
* (the star, means "everything" when interpreted by Unix or Linux)
space (the blank, " ") because "my file" will try to write down a file namde "my" and a file named "my"
$ (I guess, at least on IBM mainframe, but maybe your programs are not for mainframe ?)
And I'm sure that other forumers here will tell you a lot of other forbidden characters.
By the way, may I suggest you, if a blank or a minus is in the filename, replace it by _ (underscore) ? I see that other progs like 4image do it that way.

Thanks guys, those changes worked a treat! (I've never liked Regular Expressions, or maybe they haven't liked me) Yordan, thanks for the little extras - I've added them in also, you can never to too safe when it comes to end users and their inputs !

Cheers,
-jimmy