Link to home
Start Free TrialLog in
Avatar of PeterFrb
PeterFrbFlag for United States of America

asked on

Full-fledged "Not" clause in Regular Expressions

I am using using regular expressions in VB (reference "Microsoft VBScript Regular Expressions 5.5"), but I include Unix developers in the conversation since Unix developers use Regular Expressions so extensively.  I hope that the answer provided is true for the genre of Regular Expressions and not application specific.
Given my research into regular expressions, I have not found a "Not" clause in Regular expressions that applies for more than single characters.  
For example, say that you want to capture the entire string for people whose names appear right after a left curly bracket ("{"), and you want to capture the text between the two curly brackets, with the exclusion of two people, Bob and Roberta.  How do you do it?  
Inside square brackets, the carot symbol ("^") indicates "Not" for whatever else appears within the brackets; but outside the sqare brackets, the same symbol represents the start of the string.  In the code snippet below, I have used the carot symbol twice: the first time incorrectly (not "Bob" nor "Roberta") and the second time correctly (not a right curly bracket).  
Given that my first use of the carot for "Not" is incorrect, can I legitimatly single out Bob and Roberta for exclusion?
Thanks, ~Peter Ferber


"{(^(Bob|Roberta)[^}]+)}"

Open in new window

Avatar of ddrudik
ddrudik
Flag of United States of America image

Supply an example of a source text string, and what it should match.
Avatar of PeterFrb

ASKER

OK:
     "{John Smith is here!}" --> "John Smith is here!"
     "{Doug Kinsey makes hay.}" --> "Doug Kinsey makes hay."
     "{Bob is my guy.}" --> No match.
     "{Roberta did not show up.}" --> No match.
~Peter
You'll have to remove the leading { since vbscript regexes do not support (?<=) constructs:
Raw Match Pattern:
\{(?:(?!\b(?:Bob|Roberta)\b).)*(?=\})
 
$matches Array:
(
    [0] => Array
        (
            [0] => {John Smith is here!
            [1] => {Doug Kinsey makes hay.
        )
 
)

Open in new window

ASKER CERTIFIED SOLUTION
Avatar of ahoffmann
ahoffmann
Flag of Germany image

Link to home
membership
This solution is only available to members.
To access this solution, you must be a member of Experts Exchange.
Start Free Trial
Thank you for these answers.  I have a bit on my plate today, and I promise to give your answers a try either by end of day or Tuesday morning and, if they work, will assign credit.  Sorry for the delay, and thanks for your patience.
~Peter
Superb answer.  Sorry I was delayed in getting back to this.  I just checked the work against the four items we chose, and it was spot on!  Good work.