In essence, neither goes deep enough to resolve differences - jettero stops at the second element, and FunkyMonk stops after index 3.

FunkyMonk - in your code, "@_" inside the sort is probably not what you think it is - at that point, @_ is still the parameter passed into "sortsub". Inside the sort itself, you only have $a and $b. The "@_" comes from the outer sub.

Here is code with slightly modified data, that demonstrates the errors, and my proposed "correct" solution.

Update 2: The O.P. has correctly chosen Funkymonk's code as representing what he requested.
My code addresses a different issue - sorting to the complete depth.

While I like your solution, FunkyMonk's routine could be made to sort on all elements of an array by changing its arguments:

my $sorted = FunkyMonkSort($unsorted, 0..$#$unsorted);
[download]

Your code meets the specification to sort a 2D array where each element in every row is compared.

FunkyMonk's code solves a different problem--sort a 2D array by an arbitrary subset of elements in each row.

I spent a while looking for the "bug". There really isn't a bug, it's just that you interpreting the spec differently than FunkyMonk did.

BTW, I like the way that you called attention the the fact the NetWallaSort() is a sort function, and gets $a and $b automagically.


TGI says moo

TGI (++)- Agreed to all your points.

I had /msg'd FunkyMonk (also ++) that I had misread the OP's requirement.

I now publicly post that his post was NOT buggy, based on what the OP said he wanted, and his "@_" was indeed what he intended (after his update).

     "As you get older three things happen. The first is your memory goes, and I can't remember the other two... " - Sir Norman Wisdom

The sort I wrote was written to match the OP's spec: to sort by columns 1, 2 then 4 (which I took to mean 0, 1 and 3 in Perl terms)

Note that I updated my node a couple of hours before you posted :(

FunkyMonk - in your code, "@_" inside the sort is probably not what you think it is - at that point, @_ is still the parameter passed into "sortsub". Inside the sort itself, you only have $a and $b. The "@_" comes from the outer sub.

That's exactly what I intended

update: much less than a couple of hours:(

I think
return 1; #Pathological
should be
return 0; #Pathological
$a and $b are equal at that point, so zero should be returned.

I think some versions of sort in some versions of Perl even crashe when inconsistent results (a < b < a) are returned, something that can happen when returning non-zero for equal values.

NetWallah, That went abit over my head. So how would your code look like?

I am not clear on how I would implement this to

input:

@toBeSorted, 0, 1, 3)

output:

@sorted

Can I see what you code would look like so that I can study the correct way?




After all this is over, all that will really have mattered is how we treated each other.

The only relevant part of the code I posted is "sub NetWallahSort".

Just copy that sub into your code, and use it like:

  my @sorted =  sort NetWallahSort   @$unsorted; 
       # Or, simply "@unsorted", if @unsorted is an Array-of-Arrays,
       #     rather than a reference.
[download]

FYI - a 2-Dimensional array is technically an "Array of Array-references".

FonkyMonk makes his declaration ($unsorted) a scalar, which is a "reference to an Array of Array-references", or "a reference to a 2-d Array". As Sienfeld would say - not that there is anything wrong with that!

     "As you get older three things happen. The first is your memory goes, and I can't remember the other two... " - Sir Norman Wisdom