Re^2: Recursive subroutines with sort

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Re^3: Recursive subroutines with sort by LanX (Saint) on Jul 08, 2019 at 12:46 UTC
> but when is it useful that sub being able to recurse? what comes to mind are chained comparisons in `sort` ° `sort { $a->[0] cmp $b->[0] or $a->[1] cmp $b->[1] # * or $a->[2] cmp $b->[2] # * or ... # * } @AoA # *) only check if former was equal == 0 == false` [download] if you don't know the number of fields, recursive comparisons come in handy. I'm bu-la-zy, so constructing the recursion is left as exercise. ;-) HTH! update In hindsight ... this particular case could also be solved in a loop. So think about a more complicated data structures like trees to be sorted. In the end it's about convenience ... every loop can be expressed as recursion and vice versa. Cheers Rolf _{(addicted to the Perl Programming Language :) Wikisyntax for the Monastery FootballPerl is like chess, only without the dice} °) see examples in code from line 39 onwards	[reply] [d/l]

Replies are listed 'Best First'.

Re^3: Recursive subroutines with sort
by LanX (Saint) on Jul 08, 2019 at 12:46 UTC

> but when is it useful that sub being able to recurse?

what comes to mind are chained comparisons in sort °

 
sort { 
        $a->[0] cmp $b->[0]  
     or $a->[1] cmp $b->[1]       # *
     or $a->[2] cmp $b->[2]       # *
     or ...                       # *
    } @AoA

# *) only check if former was equal == 0 == false
[download]

if you don't know the number of fields, recursive comparisons come in handy.

I'm bu-la-zy, so constructing the recursion is left as exercise. ;-)

HTH!

update

In hindsight ... this particular case could also be solved in a loop.

So think about a more complicated data structures like trees to be sorted.

In the end it's about convenience ... every loop can be expressed as recursion and vice versa.

Cheers Rolf
_{(addicted to the Perl Programming Language :)

Wikisyntax for the Monastery
FootballPerl is like chess, only without the dice}

°) see examples in code from line 39 onwards

[reply]
[d/l]