#!/usr/bin/perl
####################  Perl "Records"  As Hashes of Lists  ###################
%bowling = ("Perry,John"   => [124,145,101,98],
            "Smith,Joe"    => [187,190,209,176,195,203],
            "Wonka,Willie" => [202,165,278]);

print "$bowling{'Perry,John'}->[2]\n";
print "$bowling{'Wonka,Willie'}[0]\n\n";
undef(%bowling);
#################  Reading the Same Records from a File  ##############

#  The comments below show the format of file "data".
#  Perry,John 124 145 101 98
#  Smith,Joe 187 190 209 176 195 203
#  Wonka,Willie 202 165 278

open(F,"data") or die "Cannot read data file.\n";

while(<F>)
{
      ($name, @scores) = split;
      $bowling{$name} = [@scores];   # $bowling{$name} = \@scores is WRONG!!!!
}

print "$bowling{'Perry,John'}->[2]\n";
print "$bowling{'Wonka,Willie'}[0]\n\n";
###################  Output Records in Key Order  #####################

foreach $name (sort keys %bowling)
{
     print "@{$bowling{$name}}\n";   #  Each key's value is a list
                                     #  ref., hence the @ dereference!
}                                    
print "\n";
########  Sending a Hash of Lists to a Function Via References  ###########

%bowling = ("Perry,John" => [124,145,101,98],
            "Smith,Joe"  => [187,190,209,176,195,203],
            "Wonka,Willie"=> [202,165,278]);

change_hash(\%bowling);
foreach $name (keys %bowling)
{
     print "@{$bowling{$name}}\n";   #######  Output #4 in id order
}     
print "\n\n";


sub change_hash
{
     my ($href) = shift;

     foreach $name (keys %$href)
     {
         $href->{$name}->[1] = 50;  #  $href->{$name}[1] works!  Adjacent
     }                              #  indexes can omit intervening arrow. 
}
##################################  Program Output  ###########################

101
202

101
202

124 145 101 98
187 190 209 176 195 203
202 165 278

202 50 278
124 50 101 98
187 50 209 176 195 203