Hello.

I was trying to convert parentheses to square brackets in my program:

#!/usr/bin/perl

use warnings;
use strict;

$\ = $/;

$_ = reverse "(a+b)*c"; # or some longer sequence

s/\)([^()]+)\(/]$1[/g;

print scalar reverse y/][/)(/r;
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OUTPUT:

syntax error at ./bracket.pl line 13, near "y/][/)(/r;"
Execution of ./bracket.pl aborted due to compilation errors.
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I guess that perl tried to interpret $1[ as element of an array @1? So I solved this problem in two ways, using:

s/\)([^()]+)\(/]$1\[/g; # '[' is not a metachar here
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and usual way

s/\)([^()]+)\(/]${1}[/g; 
# to surround the whole variable name which is interpreted inside a st
+ring
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