Question

I have a large ASP.NET project where I want to do a mass search and replace (about 3500 instances)

I want to change

If strErrorMessage.Length > 0

If strSomeString.Length > 0

If strWhatever.Length > 0

and any other similar call to the Length method from a string to the following

If Len(strErrorMessage) > 0

If Len(strSomeString) > 0

If Len(strWhatever) > 0

Anyway to reliably do this in one shot?

I can do a search and replace for something like

If *.Length > 0 --> If Len(*) > 0 

This just won’t work though as it won’t understand how to rearrange it properly. Currently have VS2010 and N++ at my disposal.

Any ideas?

Answer 1

Using the Visual Studio Find/Replace (with the regex options enabled) you can use this:

Find what: If {:a+}\.Length \> 0

Replace with: If Len(\1) \> 0

Pattern explanation:

• :a+ = the :a matches an alphanumeric char, and the + matches at least one occurrence
• {} in {:a+} = Visual Studio regex’s way of “tagging” (i.e., capturing) an expression
• \> = the > must be escaped with a backslash since it’s a metacharacter in this regex flavor.
• \1 = refers to the text matched in the tagged expression. The number 1 refers to the first (and only, in this case) tagged expression.

You can read more about the MSDN regex reference for Find/Replace here.

As I had mentioned in my comment, I think using Len() is a step backwards and ties your code down to the Microsoft.VisualBasic namespace. @drventure brought up a good point though, since calling .Length on a null value would throw an exception. Instead of checking the length you could use String.IsNullOrEmpty. In .NET 4.0 you can also use String.IsNullOrWhiteSpace.

Instead of If strErrorMessage.Length > 0 you can use:

If Not String.IsNullOrEmpty(strErrorMessage) Then
' or '
If Not String.IsNullOrWhiteSpace(strErrorMessage) Then

If you’re interested in using this you can keep the original “Find what” pattern and change the “Replace with” pattern to this: If Not String.IsNullOrEmpty(\1)