为什么Perl抱怨“不建议使用对@_的隐式拆分"?

问题描述

此代码触发以下投诉:

#!/usr/bin/perl
use strict;
use warnings;

my $s = "aaa bbb";
my $num_of_item = split(/\s+/, $s) ;
print $num_of_item;

运行代码时，Perl抱怨"Use of implicit split to @_ is deprecated".我真的没有问题的背景"，所以我希望您能帮助您解释问题所在代码.

When I run the code, Perl complains that "Use of implicit split to @_ is deprecated" .I really have no "context" for the problem, so I expect you help to explain what's wrong withthe code.

推荐答案

您在标量上下文中使用split，并且在标量上下文中将其拆分为@_数组. Perl警告您，您可能刚刚破坏了@_. (有关更多信息，请参见 perldoc拆分.)

You are using split in scalar context, and in scalar context it splits into the @_ array. Perl is warning you that you may have just clobbered @_. (See perldoc split for more information.)

要获取字段数，请使用以下代码:

To get the number of fields, use this code:

my @items = split(/\s+/, $s);
my $num_of_item = @items;

或

my $num_of_item = () = split /\s+/, $s, -1;

注意:split()的三参数形式是必需的，因为如果不指定限制，split只会分割出一个片段(超出了其中的一个)作业).

Note: The three-argument form of split() is necessary because without specifying a limit, split would only split off one piece (one more than is needed inthe assignment).

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