sorting - Sort an array in perl

Question

I have an array with elements

@a =(mem_64x128,mem_8x64,mem_8x128,mem_128x64);

I want the array to be sorted in the following manner

   mem_8x64,mem_8x128,mem_64x128,mem_128x64

But when I sort @a, the output I get is

mem_128x64
mem_64x128
mem_8x64
mem_8x128

Can anyone please help. Thanks

Answer 1

Use custom comparing function sort (perldoc):

sort {
   my ($c,$d) = $a =~ /(d+)x(d+)/;
   my ($e,$f) = $b =~ /(d+)x(d+)/;
   $c<=>$e || $d<=>$f;
} @a;

or faster one:

my %h;
@a = sort  {
   $h{$a} || ( @{$h{$a}} = $a =~ /(d+)x(d+)/ );
   $h{$b} || ( @{$h{$b}} = $b =~ /(d+)x(d+)/ );
   $h{$a}->[0] <=> $h{$b}->[0] || $h{$a}->[1] <=> $h{$b}->[1];
} @a;