Question

I’m trying to validate that a user inputs some text into a rich text box, on the server side. I don’t want to allow them to put in just HTML encoded spaces, either. I’m using an application’s built in regex validation, so I can’t have more than one pattern.

Is it possible to use only one C# regex for the following pattern?

Allow (one or more non white space characters). Don’t allow empty string:

^.*\S+.*$

-They need to enter some text. All white space not allowed:

!^\s+$ 

-Most likely white space will appear as  . Don’t allow a string of only HTML space characters:

!^( )+$

I thought that this would work but it doesn’t:

 ^.*\S+$(!(^(\s+)+$))!(^( )+$)

So these two would be a valid strings:

'lorem ipsum' 
'lorem ipsum'

Answer 1

Im not clear on what you are trying to capture… but does this work?

^((\S(?<!&nbsp;))+((\s|&nbsp;)+)?)+$

Matches:
"lorem"
"lorem ipsum"
"lorem ipsum"

Doesn’t match:
""
" "

edited for comment