Regular Expression

[Shawn B.]

Greetings,

Given the following string:

eid=6;mid={S:mid};peid={Seid};pname={Sname};;happy={R:happy}


What regular expression would I write to match the ";" but not the ";;". I
want to write a replace regex to replace the ";" with another character and
the ";;" with a ";".


Thanks,
Shawn

 

[Christof Nordiek]

Hi Shawn,

(?<!;(?!

should match only single ";".

hth
Christof

 

[Shawn B.]

(?<!;(?!

should match only single ";".

Thanks. I have a question, is the ! a not operator? It looks like you are
actually saying "match ; where no ; appears before or after" ? I'm just
trying to get more expressive with my expressions and didn't ever think to
try it this way. Thanks for the help.


Thanks,
Shawn

 

[MasterGaurav \(www.edujini-labs.com\)]

(?<!;(?!

Not quite sure but I think it will fail for:

"A;"

For the specific case given by Shawn where ';' does not appear at start or
end, how about:

[^;];[^;]

Why do we need to have a negative lookbehind ('<')?

Again, not quite sure but I think have look-aheads or look-behinds would be
costlier... correct me if I am wrong.


--
Happy Hacking,
Gaurav Vaish | www.mastergaurav.com
www.edujini-labs.com
http://eduzine.edujini-labs.com
-----------------------------------------

 

[Christof Nordiek]

Not quite sure but I think it will fail for:

"A;"

For the specific case given by Shawn where ';' does not appear at start or
end, how about:

Do you mean, the ';' in "A;" shouldn't be matched?
I'm not sure, but Shawn will know.

[^;];[^;]

Why do we need to have a negative lookbehind ('<')?

Again, not quite sure but I think have look-aheads or look-behinds would
be costlier... correct me if I am wrong.

Your not quite sure? I'm absolute not sure ;-)
Since there is a semantic difference, first it should be decided, what is
the correct expression.
If the difference doesn't matter, (f.e. because ";" at beginning or end
could not occur), then we may look, what has better performance.

Christof