select underlined text from rtf using regex

Question

i want to select the next piece of text which is underlined. You see the rtf of a richtextbox has following code for an underlines text :

\ul\i0 hello friend\ulnone\i

But the normal text looks like underlined. What i want to do is on a click of button the rtfbox should select the next piece of text which is underlined. An example piece of text is :

hello [friend your] house [looks] amazing.

imagine the words within square brackets are underlined. When i first click button1 "friend your" should be selected and on next click "looks" should be selected. Kind of keep moving forward and keep selecting it type of application. I know this can be done using regex but can't build a logic.

Any help will be appreciated. Thanks a lot :D

Answer 1

The regex would be

Dim pattern As String = "\\ul\\i0\s*((?:(?!\\ulnone\\i).)+)\\ulnone\\i"

Explanation

\\ul\\i0              # the sequence "\ul\i0"
\s*                   # any number of white space
(                     # begin group 1:
  (?:                 #   non-capturing group:
    (?!               #     negative look-ahead ("not followed by..."):
      \\ulnone\\i     #       the sequence "\ulnone\i"
    )                 #     end negative look-ahead
    .                 #     match next character (it is underlined)
  )+                  #   end non-capturing group, repeat
)                     # end group 1 (it will contain all underlined characters)
\\ulnone\\i           # the sequence "\ulnone\i"