Re^2: Inertion sort in perl

Close, but not entirely true:

>perl -le "print for sort @ARGV" 1 10 2 20
1
10
2
20
[download]

But with an explicit comparison, it works:

>perl -le "print for sort{ $a <=> $b } @ARGV" 1 10 2 20
1
2
10
20
[download]

Comment on Re^2: Inertion sort in perl Select or Download Code

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Re^3: Inertion sort in perl by Marshall (Canon) on Apr 25, 2009 at 17:15 UTC
Yes, we are on the same page here! Thanks for emphasizing the difference between ASCII vs numeric sort order! Corion is completely correct about this...there is a difference. I attach some code that I use for a GUI sort gizmo that doesn't know if it is sorting numbers or alpha-number strings. It uses normal string compare unless both items are strictly numeric and in that case, it uses the "spaceship" operator "<=>" for the compare. `sub alpha_num_cmp { my($a, $b) = @_; if (( $a =~ m/\D/) \|\| ($b =~ m/\D/) ) { #look for a non-digit return ($a cmp $b); #if so, then use string compare } return ($a <=> $b); #otherwise straight numeric comparison }` ~~[download]~~ Ok, a cut-n-paste goof...The above code was one level down in the GUI..Ooops! That code compares "columns" of similar things. Here is more code... #!usr/bin/perl -w use strict; my @a=(8,5,2,4,88,1,10,20,5,4,3,2); my @b = sort @a; print "alpha sort\n"; print "@b\n"; @b = sort {$a<=>$b}@a; print "numeric sort\n"; print "@b\n"; @b = sort alpha_num_cmp @a; print "an any sort\n"; print "@b\n"; sub alpha_num_cmp { if ( ( $a =~ m/\D/) \|\| ($b =~ m/\D/) ) { #look for a non-digit return ($a cmp $b); #if so, then use string compare } return ($a <=> $b); #otherwise straight numeric comparison } __END__ prints: alpha sort 1 10 2 2 20 3 4 4 5 5 8 88 numeric sort 1 2 2 3 4 4 5 5 8 10 20 88 an any sort 1 2 2 3 4 4 5 5 8 10 20 88 [download]	[reply] [d/l] [select]

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Re^3: Inertion sort in perl
by Marshall (Canon) on Apr 25, 2009 at 17:15 UTC

Corion is completely correct about this...there is a difference.

I attach some code that I use for a GUI sort gizmo that doesn't know if it is sorting numbers or alpha-number strings. It uses normal string compare unless both items are strictly numeric and in that case, it uses the "spaceship" operator "<=>" for the compare.

sub alpha_num_cmp 
{
  my($a, $b) = @_;
  if (( $a =~ m/\D/) || ($b =~ m/\D/) ) { #look for a non-digit
      return ($a cmp $b);  #if so, then use string compare
      }
 return ($a <=> $b); #otherwise straight numeric comparison
}
[download]

That code compares "columns" of similar things. Here is more code...

#!usr/bin/perl -w
use strict;

my @a=(8,5,2,4,88,1,10,20,5,4,3,2);

my @b = sort @a;
print "alpha sort\n";
print "@b\n";

@b = sort {$a<=>$b}@a;
print "numeric sort\n";
print "@b\n";

@b = sort alpha_num_cmp @a;
print "an any sort\n";
print "@b\n";

sub alpha_num_cmp 
{
   if ( ( $a =~ m/\D/) || ($b =~ m/\D/) ) 
   {                       #look for a non-digit
      return ($a cmp $b);  #if so, then use string compare
   }
   return ($a <=> $b); #otherwise straight numeric comparison
}

__END__
prints:
alpha sort
1 10 2 2 20 3 4 4 5 5 8 88
numeric sort
1 2 2 3 4 4 5 5 8 10 20 88
an any sort
1 2 2 3 4 4 5 5 8 10 20 88
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