use warnings; use strict; use Test::More qw(no_plan); # we're going to try doing various things to $_, # and we want to see if it changes the initial value my $initial_value = 'Some Value'; my @initial_array = qw( wun tew thuree foah fahv sex sevhun ); {#1 map perlfunc: "locally setting $_ to each element"? my $testcase = "map"; my @array = @initial_array; $_ = $initial_value; my @whateva = map{ s/^f/F/ } @array; is( $_, $initial_value, $testcase); } {#2 foreach my $testcase = "foreach"; my @array = @initial_array; $_ = $initial_value; my @whateva = (); foreach (@array) { s/^f/F/; push @whateva, $_ }; is( $_, $initial_value, $testcase); } {#3 while - this one fails my $testcase = "while"; my @array = @initial_array; $_ = $initial_value; my @whateva = (); while (@array) { $_ = pop @array; s/^f/F/; push @whateva, $_}; is( $_, $initial_value, $testcase); } {#4 while with local my $testcase = "while with explicit local"; my @array = @initial_array; $_ = $initial_value; my @whateva = (); while (@array) { local $_ = pop @array; s/^f/F/; push @whateva, $_}; is( $_, $initial_value, $testcase); } {#5 grep my $testcase = "grep"; my @array = @initial_array; $_ = $initial_value; my @whateva = grep{ m/^f/ } @array; is( $_, $initial_value, $testcase); }