[fpc-pascal] A Regular Expression failing on the borders of words

[Graeme Geldenhuys]

 When in doubt, I always recommend "Explain Regex" - there are many 
such online services. Here is one.

http://rick.measham.id.au/paste/explain.pl?regex=%5Cd%2B(.%5Cd%2B)%3F(%5BeE%5D%5Cd%2B)%3F

Simply paste your regex in the box and click the button. It will then 
analyse and explain what your regex will do and match.

If still in doubt, I recommend you take a look at RegexMagic 
[http://www.regexmagic.com/] or RegexBuddy 
[http://www.regexbuddy.com/]. These products make it super easy to 
create working regex statements. Even the 30 day trials will help.


Regards,
  - Graeme -

--
fpGUI Toolkit - a cross-platform GUI toolkit using Free Pascal
http://fpgui.sourceforge.net/


On Thursday 10/04/2014 at 06:44, luciano de souza  wrote:
> Hello all,
>
> This program compiles, but it gives a wrong output.
>
> program ertext;
> {$mode objfpc}{$H+}
>
> uses
> Sysutils, regexpr;
>
> var
> r: TRegexpr;
> i: integer;
>
> BEGIN
> r := TRegexpr.create;
> try
> r.expression := 
> '^(x\s+)*(\([A-E]\))*(\s*.*\.)+(\s+\+.*\b)*(\s+ at .*\b)*$';
> if r.exec('x (A) Write a report. +ABC +DEF @John @Mary') then
> begin
> for i := 1 to r.SubexprMatchCount do
> begin
> writeln(r.match[i]);
> readln;
> end;
> end;
>
> finally
> r.free;
> end;
> END.
>
> The input string is "x (A) Write a report. +ABC +DEF @John @Mary".
>
> The expected output was:
>
> r.match[1] -> " x" -> OK
> r.match[2] -> "(A)" -> OK
> r.match[3] -> "Write a report." -> OK
> r.match[4] -> " +ABC +DEF" -> Error
> r.match[5] -> " @John @Mary" -> Error
>
> In stead of 4 e 5, I got only 4 with the following output: " +ABC +DEF
> @John @Mary".
>
> It's true I am not have enough experience in Regular Expressions, but
> the used one seems to be very logical for me. Would Someone have any
> idea what is wrong?
>
> Best regards,
>
> --
> Luciano de Souza
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