#!/usr/bin/perl -w

#######################################################
# lab02_hash_functs
#
# try out a variety of Perl's hash functions:
# keys, values, each
#
# modified by Sharon Tuttle from "Learning Perl",
#    by Schwartz and Phoenix
#
# last modified: 9-2-04
#######################################################

%order_totals = ("chocolate"=>13, 
                 "hamburger"=>10, 
                 "tofu dog"=>12,
                );


@hold_order_totals = %order_totals;
print "@hold_order_totals\n";

# try out hash functions keys, values

@foods = keys %order_totals;
@quants = values %order_totals;

print "\nresult from keys: @foods\n";
print "result from values: @quants\n";

# in a scalar context, both keys and values return the number
# of elements in the hash;

$num_foods = keys %order_totals;
$num_quants = values %order_totals;

print "\n\$num_foods: $num_foods\n";
print "\$num_quants: $num_quants\n";

# iterating through a hash, attempt #1:

print "\ntrying foreach with a hash:\n";

foreach $item (%order_totals)
{
   print "$item\n";
}

# BETTER way to iterate through a hash: function each

print "\ntrying each and while with a hash:\n";

while ( ($food, $quant) = each %order_totals )
{
    print "$food => $quant\n";
}


# BUT --- if you need the keys in ASCIIbetical order...

print "\nin ASCIIbetical order of keys:\n";

foreach $food (sort keys %order_totals)
{
    print "$food => $order_totals{$food}\n";
}

# end of lab02_hash_functs