Using Regular Expressions to Find File Addresses

Question

How would I go about using Regular Expressions to determine if a string points to a file? (A web address of a file)

An example would be:
http://www.freewebs.com/programble/ (Does not point to a file)
http://www.freewebs.com/programble/programs/fireworks/screenshots/screen1.bmp (Does point to a file)

I would want a function to return from the above list only the second address, because it points to a file.

Answer 1

Or, if anyone has any other way (not Regular Expressions) of getting the addresses that point directly to a file, please post that aswell.

Answer 2

i don't think this is regular expressions, but give it a try....
    Dim Url As String
        Url = "www.lol.com/lol.bmp"
        Dim count As New Integer
        Dim number As Integer = 0 - 5
        number += Url.Length
        For Each c As Char In Url.Substring(0)
            If count > number Then
                If c = "." Then
                    MessageBox.Show("Points to a file")
                End If
            End If

            count += 1
        Next

Answer 3

Thank you, that seems to work.

Answer 4

you could try something like this also

Dim Url As String = "www.lol.com/lol.bmp"

If Url.Substring(Url.Length - 4, 1) = "." Then

'found . with 3 letter extension - should be a file???

End If

 

 

EDIT -

 

Actually the more i think about it this could be broken easily because if the url is something like www.lol.com then it would think it was a file.  I'm not sure the best way to handle this one.  There are quite a few things to check to make sure the extension would not be .com or .net and others.  Maybe a list of file extensions to compare the end of the url to would be best.  ???

 

Jeff

Answer 5

you should use that its far more accurate

Answer 6

That would only work on a three letter extension. What about .js, .cs, .vb, etc?

Answer 7

You are right, it has too many flaws for several reasons.  It might really be better to have a list of possible file extensions and check that the url endswith an extension contained in the list.  Not sure of a better way to do it.  Though there probably is.

 

Jeff

 

Answer 8

How could I use a list? I want it to recognize every file extension, it's not just a set of extensions that I'm looking for.

Answer 9

I wonder if it might be easier to rule out the possible domain types since there are fewer domain extensions.  If you create a generic list you can iterate through it and check if the url ends with anyting in the list. 

 

Example

Dim url_list As New List(Of String)

url_list.Add(".com")

url_list.Add(".net")

 

Dim s As String = Url.Substring(Url.LastIndexOf("."))

If url_list.Contains(s) Then

     MsgBox("not a file")

End If

 

 

or you can do this

For i As Integer = 0 To url_list.Count - 1

     If s.EndsWith(url_list(i).ToString) Then

         Exit For

         MsgBox("not a file")

     End If

Next

 

 

here is a good list of the extensions (not sure this is all of them

 

Generic .biz · .com · .info · .name · .net · .org · .pro Sponsored .aero · .asia · .cat · .coop · .edu · .gov · .int · .jobs · .mil · .mobi · .museum · .tel · .travel Infrastructure .arpa Deleted/retired .nato Reserved .example · .invalid · .localhost · .test Pseudo .bitnet · .csnet · .local · .root · .uucp · .onion/.exit

Proposed Locations .berlin · .lat · .nyc Language and nationality .bzh · .cym · .gal · .sco Technical .geo · .mail Other .kids · .post · .shop · .web · .xxx

Answer 10

Thank you. There is only one problem, I hear that people will be able to register any domeain name soon. What about when people start having www.xxx.yalu? I think I could check if theres a "." in the last few characters and make sure there is a slash before that. "www.google.ca" does have a "." in the last few characters, but no slash before that. "www.freewebs.com/programble/programs.htm" has a "." in the last few letters, and a slash before that.