use strict; use warnings; use Data::Dumper; my %hash; while(){ #chomp; $hash{$_}++ for split; } $hash{''}=2; print Dumper(\%hash); print '*'x55,"\n"; my @greparr= grep {$hash{$_} > 1} sort keys %hash; print "greparr has ", scalar @greparr, " elements.\n"; my @maparr = map {$_ if $hash{$_} > 1} sort keys %hash; print "maparr has ", scalar @maparr, " elements.\n"; my @grep2 = grep {$_ if $hash{$_} > 1} sort keys %hash; print "grep2 has ", scalar @grep2, " elements.\n"; print '*'x55,"\n"; print Dumper(\@greparr); print '*'x55,"\n"; print Dumper(\@maparr); print '*'x55,"\n"; print Dumper(\@grep2); print '*'x55,"\n"; __DATA__ 0 0 teacher students teacher students nope