本文介绍了如何从数组中减去数组?的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
当我尝试以下时
#!/usr/bin/perl
use strict;
use warnings;
use Data::Dumper;
my @bl = qw(red green blue);
my @a = qw(green yellow purple blue pink);
print Dumper [grep {not @bl} @a];
我得到一个空数组.我本来希望从 @a 中减去 @bl，所以输出是 yellow Purple pink.
I get an empty array. I would have expected that @bl was subtracted from @a, so the output was yellow purple pink.
这里出了什么问题?
推荐答案
需要将@bl转成hash来进行集差:
You need to turn @bl into a hash to perform the set difference:
my %in_bl = map {$_ => 1} @bl;
my @diff = grep {not $in_bl{$_}} @a;
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