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my @fields = ... ; my $binary = chr(0); defined( $fields[ $_ ] ) && length( $fields[ $_ ] ) and vec( $binary, +$_, 1 ) = 1 for 0 .. $#fields;
@fields = ( 'fred', undef, '', 0, 123, ' ' );; $binary = '';; ... print unpack 'b*', $binary;; 10011000