Strange thing using Replace(..) in vb.net

[Guest]

Hi,
in our application we use the following code snippet:

Dim target As String = Replace(txtLinkTarget.Text, "<SEP>", "'")
If target.StartsWith("(") AndAlso target.EndsWith(")") Then

In line 1 the text-value of of a textbox is retrieved. All occurences of
<SEP> are then replaced by an apostrophe.

However, if txtLinkTarget.Text returns an empty string, the Replace
function evaluates to Nothing, giving me a nice exception in line 2.
How is that possible?

 

[Guest]

How is that possible?

The Replace method has two Exceptions:

ArgumentNullException = original string is a null reference (Nothing in
Visual Basic).
ArgumentException = original string is an empty string ("").

http://msdn.microsoft.com/library/d...f/html/frlrfSystemStringClassReplaceTopic.asp

You need to verify that your original string is not null (Nothing) or empty
("") before calling replace.

If (Not OriginalString Is Nothing) AndAlso (Not OriginalString = "") Then

'Perform your replace and StartsWith/EndsWith here...

End If

Paul

 

[Cor Ligthert]

Reik,

I thought that all your answers are here.

http://msdn.microsoft.com/library/d...tml/frlrfsystemstringclassstartswithtopic.asp

In VBNet is a
dim a as string = nothing
not the same as
dim a as string = ""
The last is a string empty.

I hope this helps?

Cor

 

[Cor Ligthert]

Havagan,

You reference to the String.Replace while in my opinion the VB Replace is
used.

Cor

 

[Guest]

Thanks Paul

This is somewhat inconvinient, adding two additional lines to check if the
string is correct. What harm could an empty string do in the Replace
function. The function should be able to handle empty strings just like any
string object other than nothing.

 

[Guest]

Oh I thougth Havagan meant VB Replace, but I think its the same problem.