c:\temp> D:\perl58\bin\perl.exe re.pl D:\perl58\bin\perl.exe re.pl Replace against literal quoted: aaabbb Replace against literal bslashed: aaabbb Replace against variable quoted => \Q([\+\-]{\E\d\Q})\E <=: aaa([\+\-]{1})bbb Replace against variable bslashed => \(\[\\\+\\-\]\{\d\}\) <=: aaabbb c:\temp>perl re.pl perl re.pl Replace against literal quoted: aaabbb Replace against literal bslashed: aaabbb Replace against variable quoted => \Q([\+\-]{\E\d\Q})\E <=: aaa([\+\-]{1})bbb Replace against variable bslashed => \(\[\\\+\\-\]\{\d\}\) <=: aaabbb C:\temp\perl -v This is perl, v5.6.1 built for MSWin32-x86-multi-thread (with 1 registered patch, see perl -V for more detail)