perl哈希要点，哈希与数组的关系以及相互转化，哈希结构的转化（键值转换），测试关键字，

use strict;
use warnings;

my %movies;
my $film;
my %reverse_result;
my $director;
my @data;

%movies =
(
	'The Shining'       => 'Kubrick',
	'Ten Commandments'  => 'DeMille',
	'Goonies'           => 'Spielberg',
);

#输出哈希的值，输出的结果为Kubrick
print $movies{'The Shining'};

#同时输出键和值
foreach $film(keys %movies)
{
	print "$film was directed by $movies{$film}.\n";
}

#添加空格
print "\n";


#哈希结构的切换
%reverse_result=reverse %movies;
foreach $director(keys %reverse_result)
{
	print "$director directe the $reverse_result{$director}.\n"; 
}


#添加空格
print "\n";


#当哈希结构用于列表环境中时，perl会将hash重新变为由关键词和键值组成的普通列表
@data=%movies;
print "@data\n";

#添加空格
print"\n";



#得到的数组是一个分为奇数为film，偶数为director的数组，或者相反
#然后我们将数组赋值给hash
%movies=@data;
foreach $director(keys %reverse_result)
{
	print "$director directe the $reverse_result{$director}.\n"; 
}

print "The result is not change\n";

以下为输出结果：

F:\>perl\a.pl
KubrickGoonies was directed by Spielberg.
The Shining was directed by Kubrick.
Ten Commandments was directed by DeMille.

DeMille directe the Ten Commandments.
Spielberg directe the Goonies.
Kubrick directe the The Shining.

Goonies Spielberg The Shining Kubrick Ten Commandments DeMille

DeMille directe the Ten Commandments.
Spielberg directe the Goonies.
Kubrick directe the The Shining.

F:\>

测试哈希key的方法：

if(exists $hash{keyval})
{
}

删除关键字：

delete hash {keyval};

清空哈希：

%hash=（）；