@array1 = ( "1,Larry Wall" , "2,Douglas Adams");

@array2 = ( "1,Programing Perl,1", 
            "2,The Hitchhikers Guide to the Galaxy,2",
            "2,Mostly Harmless,2");

foreach (@array1) {
        ($id,$name) = split( /,/, $_);

        print "The author is $name";

        $no = grep { m/,$id$/ } @array2;

        print "We have $no books by this Author\n";

}