perlnewby:

The function you give sort has one job: to tell sort which order you want between two items: $a and $b. If you want the value in $a to sort after the value in $b, your function needs to return 1. If you want it to sort before $b, return -1.

So you don't need to figure out how to get the values, they're handed to you as $a and $b. You simply need to tell sort how to decide which order you want for any two values.

$ cat foo.pl
use strict;
use warnings;

my @list = (qw(now is the time));

sub compare {
    my ($left, $right) = @_;
    print "Comparing $left and $right.\n";
    return  1 if $left gt $right;
    return -1 if $left lt $right;
    return  0;
}

print "BEFORE: ", join(" ", @list), "!\n";

@list = sort { compare($a,$b) } @list;

print "AFTER: ", join(" ", @list), "?\n";

$ perl foo.pl
BEFORE: now is the time!
Comparing now and is.
Comparing the and time.
Comparing is and the.
Comparing the and now.
AFTER: is now the time?

[download]

Update: Added punctuation for a bit of fun...

...roboticus

When your only tool is a hammer, all problems look like your thumb.

In reply to Re^5: Need help figuring out how to order/eval the numbers by roboticus
in thread Need help figuring out how to order/eval the numbers by perlynewby

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