id	summary	reporter	owner	description	type	status	milestone	component	version	severity	resolution	keywords	cc
2556	Perl regex replacement	jcombe@…	John Maddock	"I have code that reads a lookup table from memory and then attempts to search for the word found in the lookup table in some data using a regular expression:-

(.*\b)word(\b.*)

Where this matches I call replace with the following

$1WORD$2

This falls down when the word is ""2lt"" as I get the following to search for

(.*\b)2lt(\b.*)

With replacement

$12LT$2

What happens is it sees $12 as the substring to replace and since I only have two pairs of brackets in my regular expression $12 does not exist and so in effect the 2 in my input data is lost.

I am using Perl format regular expressions (boost::regex::perl)

In Perl I can resolve this by making the replacement

${1}2LT${2}

When I do this using boost I get the literal text as above output (including ${1} etc.) not the text that I expect. Since I've told Boost to use Perl syntax I would expect a regular expression replacement in Perl and Boost to behave the same way. 

Is this a bug ?

Thanks
Jon"	Bugs	closed	Boost 1.38.0	regex	Boost 1.37.0	Problem	fixed