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Will recursive code update data in an array?

by Anonymous Monk
on Apr 25, 2001 at 00:42 UTC ( #75258=categorized question: print w/replies, xml ) Need Help??
Contributed by Anonymous Monk on Apr 25, 2001 at 00:42 UTC
Q&A  > arrays

Answer: Will recursive code update data in an array?
contributed by Masem

If you pass the array as a reference, yes, the array elements can be modified. But if you pass the array directly, a copy will be made, and only the copies will be modified, the original array will not be changed:

my @a = [ 1 .. 10 ]; by_value ( 5, @a ); # @a still is [1..10] by_ref( 5, \@a ); # @a will be [120, 240,... ] sub by_value { my ( $time, @a ) = @_; if ( $time == 0 ) return; foreach my $b ( @a ) { $b *= $time; } by_value( $time--, @a ); } sub by_ref { my ( $time, $a_ref ) = @_; if ( $time == 0 ) return; foreach my $b ( @$a_ref ) { $b *= $time; } by_ref( $time--, $a_ref ); }
Answer: Will recursive code update data in an array?
contributed by arturo

If the array has wider scope than the subroutine, then yes. Unrealistic sample follows:

my @array = (); my $counter =0; recurse(); sub recurse { push @array, $counter++; return if $counter > 25; recurse(); }

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