perl 用grep map求交集、并集、补集的例子

#!/usr/bin/perl
#
# 用grep map 获取两个列表的交集并集、补集
#

use strict;

my @a=("a","b","c","d","e");
my @b=("b","g","f","e");
print "列表a数据： @a n";
print "列表b数据: @b n";

my %a = map{$_ => 1} @a;
my %b = map{$_ => 1} @b;
my @c = map{$_ => 1} @a;     # => 操作符起到了hash赋值的作用

# @a @b 交集
my @inter = grep {$a{$_}} @b;     # 求交集
print "交集：@inter n";
# @a,@b 并集
my %merge = map {$_ => 1} @a,@b;  # 求并集
my @merge = keys (%merge);

print "并集：@merge n";

# @a,@b的补集@ca，@cb，即@a和@b相对于@merge的补集

my @ca = grep {!$a{$_}} @merge;
my @cb = grep {!$b{$_}} @merge;
print "@a的补集:@ca n";
print "@b的补集:@cb n";