I have an array @responses. Each element of this array is a hash.

I want to sort the array depending on an element of the hash, how would I do this? To be a bit more specific; each hash has a 'submitted' key containing a number pertaining to when the response in question was submitted, I want to sort the @responses array based on this value. Does that makes sense?

Anyway, I'm sure that this is possible but I'm having some trouble getting my head around the sort function I need to produce, I'd be very grateful if you could offer any help.


Yes, think it makes sense.    Is this similar:

Code:

@stuff = (        {"submitted",1010101,"person","George"},        {"submitted",1020101,"person","Mildred"},        {"submitted",1010201,"person","Fred"},        {"submitted",1020102,"person","Ginger"},        {"submitted",1020201,"person","Tom"},        {"submitted",1010001,"person","Graham"} ); @newstuff = sort bywhen @stuff; foreach $pers (@newstuff) {        print $$pers{person}." at ".$$pers{submitted}."\n";        } sub bywhen {        $$a{submitted} <=> $$b{submitted};        }

runs to give

Code:

earth-wind-and-fire:~/apr05 grahamellis$ perl phsort Graham at 1010001 George at 1010101 Fred at 1010201 Mildred at 1020101 Ginger at 1020102 Tom at 1020201 earth-wind-and-fire:~/apr05 grahamellis$

The "bywhen" sort subroutine takes inputs $a and $b (they're set by perl within its sort routine which then calls back to it. The idea is that the named routine - bywhen in this example - returns a -ve, 0 or +ve value if $a comes before $b in the sort order required, has the same sort order, or comes after.

In the example above, $a and $b - the list elements to be sorted - are references to hashes, thus the $$ notation used.  Note that I could have rewritten $$a{submitted} as $a->{submitted} - an alternative syntax that means the same thing.

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