Alternatively, with Perl versions 5.10+:

c:\@Work\Perl\monks>perl -wMstrict -le
"use 5.010;
 ;;
 my $data = '1|2|3|4|5|6|7|8|9|a|b|c|d|e|f|g|h|i';
 print qq{'$data'};
 ;;
 local our $n;
 $data =~ s{ \| (?(?{ ++$n < 10 || $n > 12 }) (*FAIL)) }{ pipe }xmsg;
 print qq{'$data'};
"
'1|2|3|4|5|6|7|8|9|a|b|c|d|e|f|g|h|i'
'1|2|3|4|5|6|7|8|9|a pipe b pipe c pipe d|e|f|g|h|i'
[download]

Update: Or, without version restrictions but with more math:

c:\@Work\Perl\monks>perl -wMstrict -le
"my $data = '1|2|3|4|5|6|7|8|9|a|b|c|d|e|f|g|h|i';
 print qq{'$data'};
 ;;
 use constant O => 10;
 use constant T =>  3;
 ;;
 my $p = $data =~ tr/|//;
 my $n = $p - O - T + 1;
 my $m = $n + T - 1;
 $data =~ s{ [|] (?= (?: [^|]* [|]){$n,$m} [^|]* \z) }{ pipe }xmsg;
 print qq{'$data'};
"
'1|2|3|4|5|6|7|8|9|a|b|c|d|e|f|g|h|i'
'1|2|3|4|5|6|7|8|9|a pipe b pipe c pipe d|e|f|g|h|i'
[download]

---

---

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! —

• How do I compose an effective node title?
• How do I post a question effectively?
• Markup in the Monastery

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:
	&		&
	<		&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.