perl切片（数组和哈希）二
切片用法可在数组和哈希中提取值
数组中取数组
my @array = qw(aa bb cc dd);my @select = @array[1,3];print "@select\n";##输出bb dd123456
哈希中取值
my %hash = ( "a" => 1, "b" => 2, "c" => 3, "d" => 4,
);my @select = @hash{qw(a c)}; ## 提取key为‘a’‘c’对应的值print "@select\n";##输出为1 31234567891011
哈希中取哈希
my %hash = ( "a" => 1, "b" => 2, "c" => 3, "d" => 4,
);my %select = %hash{qw(a c)}; ##提取key为‘a’‘c’的hashmap {print "$_=> $select{$_}\n"} keys %select;##输出为：a=> 1c=> 3