Valid file name

[Jack Russell]

Is there a simple function to test if a string is a valid file name (i.e
does not contain illegal characters etc) other than doing it the long way?

Thanks

Jack Russell

 

[Adamz5]

Hi Jack,

Simply do a check to see if file.exists

if file exists it is a valid path if not path was invalid.

--Or to open a file -- prompt the user with a file dialogue box.

hope this helps

Adam

 

[Jack Russell]

Hi Jack,

Simply do a check to see if file.exists

if file exists it is a valid path if not path was invalid.

--Or to open a file -- prompt the user with a file dialogue box.

hope this helps

Adam

I tried file exists (before posting) with an invalid name - a/b.txt and
it did not throw an exception (much to my surprise)

Jack

 

[Adamz5]

try this

regards

Adam

Imports System.IO

Public Class Form1

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles Button1.Click
' Dim f As File

If File.Exists("c:\a/b.txt ") Then
MsgBox("validpath")
Else
MsgBox("invalidpath")
End If

End Sub
End Class

 

[Simon Verona]

This would report an invalid path even if the filename is syntactically
correct but just doesn't exist!

Simon

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Dealer Management Service Ltd
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Tel: 0870 080 2300
Fax: 0870 735 0011

 

[Adamz5]

Okay here you go...
full code to check file name.


'place a textbox on form write text into it and then press button 1
'place this code in the button1_click event to check that the filename
entered in textbox 1 is fine

Dim uservalue As String
uservalue = TextBox1.Text
Dim b As Boolean = False

b = uservalue.Contains("/") Or uservalue.Contains("?") _
Or uservalue.Contains(":") _
Or uservalue.Contains("*") _
Or uservalue.Contains("""") _
Or uservalue.Contains("<") _
Or uservalue.Contains(">") _
Or uservalue.Contains("|") _
Or uservalue.Contains("?")

If b = False Then
MsgBox("Valid Filename")
Else
MsgBox("Invalid Filename")
End If

By the way this is the long way (not that long is it?)

Anyway hope this helps

Regards

Adam

 

[Patrice]

Which version ?

2.0 has a System.IO.Path.GetFullPath that should raise an Argument exception
if the path contains invalid chars (the same class exposes info about
forbidden chars for file names and paths).

 

[Jack Russell]

Okay here you go...
full code to check file name.


'place a textbox on form write text into it and then press button 1
'place this code in the button1_click event to check that the filename
entered in textbox 1 is fine

Dim uservalue As String
uservalue = TextBox1.Text
Dim b As Boolean = False

b = uservalue.Contains("/") Or uservalue.Contains("?") _
Or uservalue.Contains(":") _
Or uservalue.Contains("*") _
Or uservalue.Contains("""") _
Or uservalue.Contains("<") _
Or uservalue.Contains(">") _
Or uservalue.Contains("|") _
Or uservalue.Contains("?")

If b = False Then
MsgBox("Valid Filename")
Else
MsgBox("Invalid Filename")
End If

By the way this is the long way (not that long is it?)

Anyway hope this helps

Regards

Adam

Yes that is basically what I did but knowing MS there are other things
that make a file name invalid so I thought there might be a system
function that checked all possibilities. Anyway thanks for everyones
thoughts.

Jack

 

[Claes Bergefall]

Try Path.GetFileName or Path.GetDirectoryName (or both). Both will throw an
exception if invalid characters are found in the string. If you need a list
of invalid characters you can get them by using Path.GetInvalidFileNameChars
and Path.GetInvalidPathChars

/claes

 

[Jack Russell]

Try Path.GetFileName or Path.GetDirectoryName (or both). Both will throw an
exception if invalid characters are found in the string. If you need a list
of invalid characters you can get them by using Path.GetInvalidFileNameChars
and Path.GetInvalidPathChars

/claes

Thanks for that

 

[Jack Russell]

Claes,

That works for some characters but not all ? and / are not valid but it
does not throw an exception for them.

Jack

 

[=?ISO-8859-1?Q?G=F6ran_Andersson?=]

Use the array of invalid characters from the Path class:

If fileName.IndexOfAny(System.IO.Path.GetInvalidPathChars()) <> -1 Then

 

[Herfried K. Wagner [MVP]]

Use the array of invalid characters from the Path class:

If fileName.IndexOfAny(System.IO.Path.GetInvalidPathChars()) <> -1 Then

ACK, but note that this won't guarantee the validity of the filename because
'GetInvalidPathChars' doens't necessarily return all invalid path characters
and even a path that doesn't contain any of these characters still may not
be valid.

 

[C-Services Holland b.v.]

Use the array of invalid characters from the Path class:

If fileName.IndexOfAny(System.IO.Path.GetInvalidPathChars()) <> -1 Then

This would qualify:
"c:\foo\::bar:\d\\foo" as valid. The above method will only tell you if
it contains invalid characters, but it will not tell you if a path is
actually a valid path.

 

[GhostInAK]

Hello Jack,

On XP SP1 or 2k3 there is: CheckNameLegalDOS8Dot3() exported by Kernel32.dll.
It obviously does not work on long filenames.. so don't forget about GetShortPathName()

-Boo