I was going to point out the same thing, and that doing it the Perl way is actually faster, but it turns out ikegami's XOR trick is slightly faster: 
use Benchmark;
 
sub xor_swap
{
    my($num1x,$num2x) = @_;
    $num1x ^= $num2x; $num2x ^= $num1x; $num1x ^= $num2x;
}
 
sub perl_swap
{
    my($num1x,$num2x) = @_;
    ($num1x,$num2x)=($num2x,$num1x);
}
 
timethese (1_000_000, {
    xor_swap => sub { xor_swap(38,970); },
    perl_swap => sub { perl_swap(38,970); }
});

[download]

Results: 

Benchmark: timing 1000000 iterations of perl_swap, xor_swap...
 perl_swap:  5 wallclock secs ( 4.87 usr +  0.00 sys =  4.87 CPU) 
             @ 205338.81/s (n=1000000)
  xor_swap:  4 wallclock secs ( 4.23 usr +  0.00 sys =  4.23 CPU) 
             @ 236406.62/s (n=1000000)

[download]

In reply to Re^3: Extraction of List of Coordinates by sgifford
in thread Extraction of List of Coordinates by EchoAngel

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