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Re^2: Editing Listed Data

by jtucker (Initiate)
on Mar 25, 2013 at 00:47 UTC ( #1025207=note: print w/ replies, xml ) Need Help??


in reply to Re: Editing Listed Data
in thread Editing Listed Data

Yes, I am aware of the logic of my question. What I an hung on is the third bullet. How Do I iterate through the array, yet compare the next item against the former?


Comment on Re^2: Editing Listed Data
Re^3: Editing Listed Data (index, stack)
by Anonymous Monk on Mar 25, 2013 at 01:03 UTC

    How Do I iterate through the array, yet compare the next item against the former?

    You use an index, or you keep a stack

    The index approach, its missing boundary checking ( ; beware of off-by-one errors

    my @stuff = 0 .. 9; for my $ix ( 0 .. $#stuff ){ my $item = $stuff[$ix]; my $prev = $stuff[$ix-1]; my $next = $stuff[$ix+1]; }

    The stack approach

    my @stuff = 0 .. 9; my $lastitem = ""; for my $item ( @stuff ){ my $next = $item; if( $item eq $lastitem ){ print "they measure up\n"; } $lastitem = $item; }

    Oh, but you $lastitem is not an array, right

    my @stuff = 0 .. 9; my @lastitem ; for my $item ( @stuff ){ my $next = $item; if( @lastitem and $item eq $lastitem[-1] ){ print "they measure up\n"; } push @lastitem, $item; shift @lastitem while 3 == @lastitem; ### keep at most 3 last items }

      And I didn't preview enough :) or test the logic   shift @lastitem while  @lastitem > 3; ### keep at most 3 last items

        Thanks! That was just the sort of stimulation I needed.

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