The interesting part is the sort block. It consists of two expressions, $g2o{$a} cmp $g2o{$b} and $a <=> $b.
The cmp operator returns three possible values, +1, 0 or -1, depending on whether the left side is greater, equal or smaller than the right side when compared as strings. The same holds true for the <=> ("spaceship") operator, except the comparison is done as numbers.
So putting this together, the sort block first compares $g2o{$a} to $g2o{$b} as strings, and if the two are equal as strings it compares $a and $b as numbers to determine which comes first.
Basically the sort block seems to sort first on the values of %g2o and then on the numerical value of @allgs.
PS: Plz right n full English wrds - it maeks it easier 4 us 2 hlp u. Txtspk might be OK for your mobile but not here.
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Ah...thank you bart & Corion for the clarification. Now I know what it's really doing.
--Rob
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The items from @allgs (which would appear to be numbers) will be sorted according to their associated value in the hash %g2o (compared as string), or, if equal, the smallest value (as a number) comes first.
For example:
%g2o = ( 128 => 'a',
13 => 'b',
34 => 'a',
28 => 'c' );
@allgs = (128, 13, 34 );
@allgsplane = sort { ($g2o{$a} cmp $g2o{$b}) || ($a <=> $b) } @allgs;
print "@allgsplane\n";
prints
34 128 13
All items with the value 'a' in the hash (34, 128) come before the item with value 'b' (13), because 'a' comes before 'b', but since there are two items with 'a', the smaller one (34) comes before the larger one (128).
Note that my hash contains more items than the list I'm sorting, but those will simply be ignored.
If the hash contains fewer items than the list, then it'll still work, with the missing items getting a default value of 0 (actually undef, but numerically, that is 0), but with "use of unitialized value" warnings. | [reply]
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