Jeff Westman wrote:
> Hi,
>
> I need to do a sort on a couple of column ranges.
>
> I want to be able to do a primary sort, on say, columns 21-25 and
> then a secondary sort on columns 40-49.
>
> Any ideas on how to approach this?
Assuming you're numbering columns from 1:
@rows = sort { substr($a, 20, 5) cmp substr($b, 20, 5)
|| substr($a, 49, 10) cmp substr($b, 49, 10) } @rows;
If you're numbering columns from 0, adjust the offsets above.
The general concept for multi key sorting is to combine the comparisons with
a logical "or" operation.
John Krahn gave you a sort of modified "Schwartzian Transform" (did I spell
that right?) approach which is faster if you have a large number of rows to
process, but a bit less clear...
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