use Benchmark qw(cmpthese);

my $size = $ARGV[0] || 1000;

my @array = (1..$size);

sub undef_it {
	undef @array;
	$array[$_]=$_ foreach (0..$size-1);
	return;
}

sub empty_it {
	@array = ();
	$array[$_]=$_ foreach (0..$size-1);
	return;
}

sub empty_elements {
	undef $_ for @array;
	$array[$_]=$_ foreach (0..$size-1);
	return;
}

sub assign_list_of_undefs {
	@array = (undef) x $size;
	$array[$_]=$_ foreach (0..$size-1);
	return;
}

sub undef_resize {
	undef @array; $#array = $size;
	$array[$_]=$_ foreach (0..$size-1);
	return;
}

sub empty_resize {
	@array = (); $#array = $size;
	$array[$_]=$_ foreach (0..$size-1);
	return;
}

cmpthese( -10, {
	undef_it => \&undef_it,
	empty_it => \&empty_it,
	empty_elements => \&empty_elements,
	assign_list_of_undefs => \&assign_list_of_undefs,
	undef_resize => \&undef_resize,
	empty_resize => \&empty_resize,
});

##</code><code>##

V:\Web\Distributor>c:\temp\benchEmpty.pl 100
                         Rate undef_it assign_list_of_undefs empty_elements undef_resize empty_it empty_resize
undef_it              41651/s       --                   -1%            -1%          -4%     -10%         -10%
assign_list_of_undefs 41936/s       1%                    --            -0%          -4%     -10%         -10%
empty_elements        41948/s       1%                    0%             --          -4%     -10%         -10%
undef_resize          43501/s       4%                    4%             4%           --      -6%          -6%
empty_it              46415/s      11%                   11%            11%           7%       --          -0%
empty_resize          46509/s      12%                   11%            11%           7%       0%           --

V:\Web\Distributor>c:\temp\benchEmpty.pl 100
                         Rate undef_it empty_elements undef_resize assign_list_of_undefs empty_resize empty_it
undef_it              41006/s       --            -3%          -3%                   -5%          -9%     -11%
empty_elements        42097/s       3%             --          -1%                   -3%          -7%      -9%
undef_resize          42406/s       3%             1%           --                   -2%          -6%      -8%
assign_list_of_undefs 43229/s       5%             3%           2%                    --          -4%      -7%
empty_resize          45131/s      10%             7%           6%                    4%           --      -2%
empty_it              46280/s      13%            10%           9%                    7%           3%       --

V:\Web\Distributor>c:\temp\benchEmpty.pl
                        Rate assign_list_of_undefs empty_elements empty_resize undef_resize undef_it empty_it
assign_list_of_undefs 4540/s                    --            -2%          -4%          -6%      -8%      -8%
empty_elements        4621/s                    2%             --          -3%          -5%      -6%      -7%
empty_resize          4745/s                    5%             3%           --          -2%      -4%      -4%
undef_resize          4841/s                    7%             5%           2%           --      -2%      -2%
undef_it              4919/s                    8%             6%           4%           2%       --      -1%
empty_it              4951/s                    9%             7%           4%           2%       1%       --

V:\Web\Distributor>c:\temp\benchEmpty.pl 10000
                       Rate assign_list_of_undefs empty_elements undef_it undef_resize empty_it empty_resize
assign_list_of_undefs 447/s                    --            -2%      -6%          -6%     -10%         -10%
empty_elements        454/s                    2%             --      -5%          -5%      -8%          -8%
undef_it              476/s                    7%             5%       --          -0%      -4%          -4%
undef_resize          477/s                    7%             5%       0%           --      -4%          -4%
empty_it              494/s                   11%             9%       4%           4%       --          -0%
empty_resize          496/s                   11%             9%       4%           4%       0%           --

V:\Web\Distributor>c:\temp\benchEmpty.pl 10000
                       Rate empty_elements assign_list_of_undefs undef_it undef_resize empty_it empty_resize
empty_elements        454/s             --                   -0%      -4%          -6%      -9%         -10%
assign_list_of_undefs 456/s             0%                    --      -4%          -6%      -8%          -9%
undef_it              473/s             4%                    4%       --          -2%      -5%          -6%
undef_resize          483/s             6%                    6%       2%           --      -3%          -4%
empty_it              498/s            10%                    9%       5%           3%       --          -1%
empty_resize          504/s            11%                   10%       6%           4%       1%           --

##</code><code>##

@a = ()[0..50];
print $#a;