Your first two examples would raise warnings galore when handling non numeric values, and the second example is simply an alphabetic sort, equivelent to sort @a

use warnings;
use strict;
my @a = qw( 2 two 1 11 12 one 3abcd 6foo );
print join( " ", sort { $a <=> $b || $a cmp $b } @a ), "\n";

__END__
Argument "two" isn't numeric in numeric comparison (<=>) at c:\temp\so
+rt.pl line 4.
Argument "one" isn't numeric in numeric comparison (<=>) at c:\temp\so
+rt.pl line 4.
Argument "3abcd" isn't numeric in numeric comparison (<=>) at c:\temp\
+sort.pl line 4.
Argument "6foo" isn't numeric in numeric comparison (<=>) at c:\temp\s
+ort.pl line 4.
one two 1 2 3abcd 6foo 11 12
[download]

and

#...
print join( " ", sort { $a cmp $b || $a <=> $b } @a ), "\n";

__END__
1 11 12 2 3abcd 6foo one two
[download]

Yves / DeMerphq
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Writing a good benchmark isnt as easy as it might look.