gi1 VERSION cds1
gi2 VERSION cds2
.      .     .
.      .     .
.      .     .


##</code><code>##

#!/usr/bin/perl
use strict;
use warnings;

my %info = ('gi' => "", 'version' => "", 'cds' => ""); 
# here we collect all information

sub flush_info {
        # print out all information:
	   		  print "$info{gi}"."\t"."$info{version}"."\t"."$info{cds}\n";
		%info = ();
		};

my $data = '/DATA/GenBankFile.gb'; # GenBank file is located at C:\DATA
open (INFILE, '<', $data) or die "Cannot!\n";

while (<INFILE>) {
    last if m!//$!;
	
	if (m!^VERSION.*\w:(\d+)! ) {
		$info{version} = $1;
		}
	
	elsif (m!GI:(\d+)!) {
        if ($info{cds}) { # we are in a CDS block 
			$info{gi} = $1;
			};
		} 
		
		elsif (m!^\s+CDS\s+(.*)!) {
				# a new gene information has started
				flush_info();
        
				# now remember the CDS
				$info{cds} = $1;
			}   
		
		else {warn "Ignoring unknown line [$_]\n";};
};

# Output any leftover information:
flush_info();


##</code><code>##

LOCUS       NC_0000230           600020 bp    DNA     linear   CON 21-APR-2007
VERSION     NC_000023.10  GI:123456789
     CDS             join(11111..222222,333333..444444)
                     /db_xref="GI:55555555"
     CDS             join(66666..7777777,888888..99999)
					 /db_xref="GI:10101010"
//


##</code><code>##

Ignoring unknown line [LOCUS       NC_0000230           600020 bp    DNA     linear   CON 21-APR-2007
]
Use of uninitialized value $info{"version"} in string at C:\Perl\bin\wtf16.pl line 12, <INFILE> line 5.
Use of uninitialized value $info{"version"} in string at C:\Perl\bin\wtf16.pl line 12, <INFILE> line 7.
	123456789	
55555555		join(11111..222222,333333..444444)
10101010		join(66666..7777777,888888..99999)


##</code><code>##

sub flush_info {
        # print out all information:
	   		next print "$info{gi}"."\t"."$info{version}"."\t"."$info{cds}\n" if ($info{gi} or $info{version} or $info{cds} eq undef;
		%info = ();
		};