in reply to Control loop 2D array

Like this? :) 

#! perl -slw
use strict;

my @AoA = (
   [ '1', '2', '10' ],
   [ '3', '4', '5'  ],
   [ '6', '8', '11'  ],
   [ '0', '7',  '9'  ],
);

my @A = qw(0 0 0 0 1 2 0 0 1 0 1 0);

my( $i, $j ) = ( 0, 0 );

$j++ < $#{ $AoA[ $i ] } or $i++, $j=0
    while $i < @AoA and not $A[ $AoA[$i][$j] ];

## Updated per [ysth]'s observation below
print $i == @AoA ? 'not found' : "i:$i j:$j"; 


__END__
C:\test>junk
i:0 j:2

[download]
Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
"Science is about questioning the status quo. Questioning authority".
In the absence of evidence, opinion is indistinguishable from prejudice.
"Too many [] have been sedated by an oppressive environment of political correctness and risk aversion."

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Re^2: Control loop 2D array
by ysth (Canon) on Jun 17, 2007 at 09:13 UTC
    How about a deobfuscated version?
[reply]

      Not very satisfying because of the need to use a 'goto' to quit the loops early, and the need to duplicate the index vars because Perl localises them to loop even if they are pre-existing vars.

      I tried suggesting that the latter behaviour was a bug a while ago and got shouted down. 

      #! perl -slw
use strict;

my @AoA = (
   [ '1', '2', '11' ],
   [ '3', '3', '6'  ],
   [ '6', '8', '11'  ],
   [ '0', '7',  '9'  ],
);

my @A = qw(0 0 0 0 1 2 0 0 1 0 1 0);

my( $p, $q );
OUTER: for my $i ( 0 .. $#AoA ) {
    for my $j ( 0 .. $#{ $AoA[ $i ] } ) {
        ( $p, $q ) = ( $i, $j ) and last OUTER
            if $A[ $AoA[ $i ][ $j ] ];
    }
}
print "i:$p j:$q";

      [download]

      I'm not sure why you are using the outer loop below?

      Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
      "Science is about questioning the status quo. Questioning authority".
      In the absence of evidence, opinion is indistinguishable from prejudice.
[reply]
[d/l]
        I'm not sure why you are using the outer loop below?
        A different interpretation of "the first occurence to in the second array is not zero"; mine prints 1 1. No idea which interpretation (if either) is actually what is wanted.

        I like that your new version reports undefs instead of (@AoA, 0) if there is no match.

[reply]

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