Dear throop,
Yes it is case sensitive. 

(transcription AND factor) NOT (control OR regulat)

[download]
means both the words transcription,factor has to be present but not control,regulat.

No 3 operators AND,OR,NOT is used.

given (NOT blood AND soil) what do you want extracted?

NOT should not be the first i.e only words should be the first term followed by NOT|OR|AND.

Actually i have a text file with some paragraph which includes these words.

If user enters like this 

((transcription AND factor) NOT (control OR regulat) AND (promoter) NO
+T(TATABOX))

[download]

It should get the words (transcription AND factor) AND (promoter) to be highlighted not the terms control,regulat,tatabox.

For that i have collect NOT terms in one array and other terms in other array.

Dearest Archana,
Tell us more about these oddly-formed logical expressions:
Is case significant?
Is (transcription AND factor) NOT (control OR regulat) to be understood as (transcription AND factor)AND NOT(control OR regulat)
Will there be other operators besides AND, OR and NOT? (eg XOR, !, NAND)
How should NOT scope? eg, given (NOT blood AND soil) what do you want extracted?
Where will these odd expressions be coming from? User type-in?
What do you want done with unbalanced parens?
throop

20070911 Janitored by Corion: Added formatting, code tags, as per Writeup Formatting Tips

In reply to Re^2: Regular expreesion for extraction of words by Archana
in thread Regular expreesion for extraction of words by Archana

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.