#!/usr/bin/env perl

my %h=('a' => 1, 'b' => 2, 'c' => 3);

print "using foreach \n";
foreach (keys %h){
 print "$_ $h{$_} \n";
}

print "using while each \n";
while (my ($k,$v) = each %h){
 print "$k $v \n";
}


##### p111 a
#!/usr/bin/env perl

my %h=('a' => 1, 'b' => 2, 'c' => 3);

while (my ($k, $v) = each %h){
 print "$k $v\n";
}

if (exists $h{'d'}){
 print "there is d\n";
}
else {
 print "no d\n";
}

print "$h{'a'} \n";
delete $h{'a'};
print "$h{'a'} \n";

#### count words
#!/usr/bin/env perl

print "pls input word, one word in each line \n";

my %h;

while (<>){
 chomp;
 $h{$_}++;
}

foreach (keys %h){
 print "$_ $h{$_}\n";
}