some good advice has been given above. if performance is of any concern, you'll save a little time by compiling the regex only once, by using the -o modifier, such as my $exp = $source =~ s/$group//go; to borrow gmax's solution for illustration.

of course, direct interpolation of the pattern will be even faster, such as my $exp = $source =~ s/BC//g;

my benchmark results look like:

C:\WINDOWS\Desktop>perl test_regex-o.pl
Benchmark: timing 100000 iterations of s_direct, s_witho, s_withouto..
+.
  s_direct:  4 wallclock secs ( 3.02 usr +  0.00 sys =  3.02 CPU) @ 33
+112.58/s (n=100000)
   s_witho:  4 wallclock secs ( 3.41 usr +  0.00 sys =  3.41 CPU) @ 29
+325.51/s (n=100000)
s_withouto:  5 wallclock secs ( 4.28 usr +  0.00 sys =  4.28 CPU) @ 23
+364.49/s (n=100000)

[download]

~Particle

In reply to Re: Converting BCBCBCBCBCCCB to (BC)^{5}CCB by particle
in thread Converting BCBCBCBCBCCCB to (BC)^{5}CCB by fishfork

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.