join '', map { $_, $hash{$_} } ( qw/ page chap / ); #### { page => 'chappage', chap => '' }, { page => '', chap => 'pagechap' }, #### join "\0", map { $_, $hash{$_} } ( qw/ page chap / ); #### join 'xyx', map { s/x/xx/g; $_ } map { $_, $hash{$_} }, qw/ page chap /; #### join 'xyx', map { s/x/xx/g; $_ } map $hash{$_}, qw/ page chap /;