Re^4: Map Vs Foreach

Some more benchmarking:

my @data = (1..8000000);
foreach my $x (@data) { push @arr, ($x+2); }
@arr1 = map { $_+ 2 } @data;
@arr2 = map { push @arr2, ($_+ 2) } @data;
[download]

resulted in the following measurement-output:

Time taken by foreach loop was 2 wallclock secs ( 2.27 usr 0.03 sys + 0.00 cusr 0.00 csys = 2.30 CPU) seconds
Time taken by map block was 4 wallclock secs ( 3.39 usr 0.34 sys + 0.00 cusr 0.00 csys = 3.73 CPU) seconds
Time taken by map block (with push) was 5 wallclock secs ( 4.63 usr 0.05 sys + 0.00 cusr 0.00 csys = 4.67 CPU) seconds

best regards, Rata
(a bit surprised about the performance-differences)(btw.: ActiveState perl 5.8.8)

Update
As Ikegami pointed out correctly (thanks!!), the line with @arr2 is wrong. Changing it to

map { push @arr2, ($_+ 2) } @data;

results in

Time taken by map block (with push) was 3 wallclock secs ( 2.33 usr 0.00 sys + 0.00 cusr 0.00 csys = 2.33 CPU) seconds

being similar fast as the foreach ...

Comment on Re^4: Map Vs Foreach Select or Download Code

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Re^5: Map Vs Foreach by ikegami (Patriarch) on Nov 26, 2009 at 16:16 UTC
that last line is buggy. `@arr2 = map { push @arr2, ($_+ 2) } @data;` [download] should be `map { push @arr2, ($_+ 2) } @data;` [download]	[reply] [d/l] [select]