Question

    my %seen;
    @seen{@sender} = ();
    my @merged = (@sender, grep{!exists $seen{$_}} @receiver);


    my $c1 = @merged;
    print $c1, "\n";


    @hash{@merged} = ();
    my @email = keys %hash;

    my $c2 = @email;

    print $c2, "\n";

这是我在标题中为此目的编写的代码部分。

c1打印1409，而c2打印仅493。我想知道哪里出错了几乎缺少1000个元素（不在哈希的密钥中）？

或者，如果我这样做：

    foreach (@merged) {
        $hash{$_} = ();
    }
    # @hash{@merged} = ();
    my @email = keys %hash;

分配键，它仍然只给我493个键，几乎缺少1000个键。

感谢。

Answer 1

my %seen;
@seen{@sender} = ();
my @merged = (@sender, grep{!exists $seen{$_}} @receiver);

混合使用两种方法来查找唯一值，而不做任何一项。要获取唯一值，请将上面的内容更改为

my %seen;
@seen{@sender} = ();
@seen{@receiver} = ();
my @merged = keys(%seen);

或

my %seen;
my @merged = grep !$seen{$_}++, @sender, @receiver;

后者保留了秩序。

我想使用一个元素数组作为哈希的键，但缺少一些键

1 个答案: