程嶏清单4-8.txt

< linux网络编程工具>>配套源码

# %food_color as per Introduction
sub print_foods {
    my @foods = keys %food_color;
    my $food;
    print "Keys: @foods\n";
    print "Values: ";
    foreach $food (@foods) {
        my $color = $food_color{$food};
        if (defined $color) {
            print "$color ";
        }
else {
            print "(undef) ";
        }
    }
    print "\n";
}
%food_color = (
                Apple  => "red",
                Banana => "yellow",
                Lemon  => "yellow",
                Carrot => "orange"
               );
print "Initially:\n";
print_foods();
print "\nWith Banana undef\n";
undef $food_color{"Banana"};
print_foods();
print "\nWith Banana deleted\n";
delete $food_color{"Banana"};
print_foods();