my $string=" \aabc123def!*#\n"; $string=~s{ ([[:digit:]]+) |([[:alpha:]]+) |([[:punct:]]+) |([[:space:]]+) |([[:cntrl:]]+) |(.) } { defined($1) ? '[[:digit:]]{'.length($1).'}' : defined($2) ? '[[:alpha:]]{'.length($2).'}' : defined($3) ? '[[:punct:]]{'.length($3).'}' : defined($4) ? '[[:space:]]{'.length($4).'}' : defined($5) ? '[[:cntrl:]]{'.length($5).'}' : "\Q$+\E" # anything else? }gex; print $string;