blocks|key|1241390|text|Perl6具有自动附加\n的say函数。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1241391|还可以在Perl5.10或5.12中使用say，如果添加了|1241392|use+feature+qw(say);|code-block|syntax|javascript|1241393|到你程序的开头。或者，您可以使用Modern::Perl来获取此功能和其他功能。|1241394|有关更多详细信息，请参阅perldoc+feature。|1241395|entityMap|0|LINK|mutability|MUTABLE|url|http://search.cpan.org/~chromatic/Modern-Perl-1.03/lib/Modern/Perl.pm|1|http://perldoc.perl.org/feature.html#The-%2527say%2527-feature^0|B|2|E|3|0|K|3|0|0|G|C|0|0|C|F|1|0^^$0|@$1|2|3|4|5|6|7|10|8|@$9|11|A|12|B|C]|$9|13|A|14|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|15|8|@$9|16|A|17|B|C]]|D|@]|E|$]]|$1|H|3|I|5|J|7|18|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|19|8|@]|D|@$9|1A|A|1B|1|1C]]|E|$]]|$1|O|3|P|5|6|7|1D|8|@]|D|@$9|1E|A|1F|1|1G]]|E|$]]|$1|Q|3|-4|5|6|7|1H|8|@]|D|@]|E|$]]]|R|$S|$5|T|U|V|E|$W|X]]|Y|$5|T|U|V|E|$W|Z]]]]

Perl 6 has the <code>say</code> function that automatically appends <code>\n</code>.

You can also use <code>say</code> in Perl 5.10 or 5.12 if you add

<pre><code>use feature qw(say);
</code></pre>

to the beginning of your program. Or you can use <a href="http://search.cpan.org/~chromatic/Modern-Perl-1.03/lib/Modern/Perl.pm" rel="noreferrer">Modern::Perl</a> to get this and other features.

See <a href="http://perldoc.perl.org/feature.html#The-%27say%27-feature" rel="noreferrer">perldoc feature</a> for more details.

blocks|key|1026653|text|如果不能选择Perl+5.10%2B，这里有一个简单的近似方法。这并不完全相同，因为当它的第一个arg是一个句柄时，say有一些魔力，但对于打印到STDOUT：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1026654|sub+say+{print+@_,+"\n"}

say+'hello';|code-block|syntax|javascript|1026655|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

If Perl 5.10+ is not an option, here is a quick and dirty approximation. It's not exactly the same, since say has some magic when its first arg is a handle, but for printing to STDOUT:

<pre><code>sub say {print @_, "\n"}

say 'hello';
</code></pre>

blocks|key|1026717|text|您编写print语句的方式是不必要的冗长。没有必要将换行符分隔成它自己的字符串。这就足够了。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1026718|print+"hello.\n";|code-block|syntax|javascript|1026719|这种认识通常会使你的编码变得更容易。|1026720|除了使用use+feature+"say"、use+5.10.0或use+Modern::Perl获得内置的say特性之外，我还将介绍perl5i，它在缺省情况下会打开许多缺少的Perl5特性。|offset|length|style|CODE|1026721|entityMap|0|LINK|mutability|MUTABLE|url|http://search.cpan.org/dist/perl5i^0|0|0|0|4|H|M|A|X|G|1I|3|1V|6|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|X|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Y|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|Z|8|@$K|10|L|11|M|N]|$K|12|L|13|M|N]|$K|14|L|15|M|N]|$K|16|L|17|M|N]]|9|@$K|18|L|19|1|1A]]|A|$]]|$1|O|3|-4|5|6|7|1B|8|@]|9|@]|A|$]]]|P|$Q|$5|R|S|T|A|$U|V]]]]

The way you're writing your print statement is unnecessarily verbose. There's no need to separate the newline into its own string. This is sufficient.

<pre><code>print "hello.\n";
</code></pre>

This realization will probably make your coding easier in general.

In addition to using <code>use feature "say"</code> or <code>use 5.10.0</code> or <code>use Modern::Perl</code> to get the built in <code>say</code> feature, I'm going to pimp <a href="http://search.cpan.org/dist/perl5i" rel="noreferrer">perl5i</a> which turns on a lot of sensible missing Perl 5 features by default.

blocks|key|1241631|text|也许您希望使用以下命令将输出记录分隔符更改为换行符：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1241632|local+$\+=+"\n";|offset|length|style|CODE|1241633|$+perl+-e+'print+q{hello};print+q{goodbye}'+%7C+od+-c
0000000++++h+++e+++l+++l+++o+++g+++o+++o+++d+++b+++y+++e++++++++++++++++
0000014
$+perl+-e+'$\+=+qq{\n};+print+q{hello};print+q{goodbye}'+%7C+od+-c
0000000++++h+++e+++l+++l+++o++\n+++g+++o+++o+++d+++b+++y+++e++\n++++++++
0000016|code-block|syntax|javascript|1241634|更新:我的答案是能力，而不是明智。我不认为在行尾添加"\n“是一件”烦人“的事情，但如果有人真的想要避免它们，这是一种方法。如果我必须维护一些使用这种技术的代码，我可能会立即重构它。|1241635|entityMap^0|0|0|G|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|R|8|@$D|S|E|T|F|G]]|9|@]|A|$]]|$1|H|3|I|5|J|7|U|8|@]|9|@]|A|$K|L]]|$1|M|3|N|5|6|7|V|8|@]|9|@]|A|$]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

Perhaps you want to change your output record separator to linefeed with:

<code>local $\ = "\n";</code>

<pre><code>$ perl -e 'print q{hello};print q{goodbye}' | od -c
0000000 h e l l o g o o d b y e 
0000014
$ perl -e '$\ = qq{\n}; print q{hello};print q{goodbye}' | od -c
0000000 h e l l o \n g o o d b y e \n 
0000016
</code></pre>

Update: my answer speaks to capability rather than advisability. I don't regard adding "\n" at the end of lines to be a "pesky" chore, but if someone really wants to avoid them, this is one way. If I had to maintain a bit of code that uses this technique, I'd probably refactor it out pronto.

blocks|key|1026554|text|在Perl6中有一个say函数|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1026555|entityMap|0|LINK|mutability|MUTABLE|url|http://perlcabal.org/syn/Differences.html#say()^0|A|3|A|3|0|0^^$0|@$1|2|3|4|5|6|7|N|8|@$9|O|A|P|B|C]]|D|@$9|Q|A|R|1|S]]|E|$]]|$1|F|3|-4|5|6|7|T|8|@]|D|@]|E|$]]]|G|$H|$5|I|J|K|E|$L|M]]]]

In Perl 6 there is, the <a href="http://perlcabal.org/syn/Differences.html#say()" rel="nofollow noreferrer"><code>say</code></a> function

blocks|key|1241749|text|如果您坚持使用5.10之前的版本，那么上面提供的解决方案将无法完全复制say功能。例如|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1241750|sub+say+{+print+@_,+"\n";+}|code-block|syntax|javascript|1241751|不能与调用一起工作，比如|1241752|say+for+@arr;|1241753|或|1241754|for+(@arr)+{
++++say;
}|1241755|..。因为上面的函数不像print和真实的say函数那样作用于隐式全局$_。|1241756|为了更精确地复制perl+5.10%2B+say，您需要此函数|1241757|sub+say+{
++++if+(@_)+{+print+@_,+"\n";+}
++++else+{+print+$_,+"\n";+}
}|1241758|它现在的行为是这样的|1241759|my+@arr+=+qw(+alpha+beta+gamma+);
say+@arr;
#+OUTPUT
#+alphabetagamma
#
say+for+@arr;
#+OUTPUT
#+alpha
#+beta
#+gamma
#|1241760|perl6中内置的say的行为略有不同。使用say+@arr或@arr.say调用它不仅会连接数组项，还会用列表分隔符将它们分开打印。要在perl5中复制它，您可以执行以下操作|1241761|sub+say+{
++++if+(@_)+{+print+join($",+@_)+.+"\n";+}
++++else+{+print+$_+.+"\n";+}
}|1241762|$"是全局列表分隔符变量，如果您使用的是English.pm，则is为$LIST_SEPARATOR|1241763|它现在的行为将更像perl6，如下所示|1241764|say+@arr;
#+OUTPUT
#+alpha+beta+gamma
#|1241765|entityMap^0|Z|3|0|0|0|0|0|0|C|5|L|3|Z|2|0|J|3|0|0|0|0|9|3|M|8|V|8|0|0|0|2|K|A|Z|F|0|0|0^^$0|@$1|2|3|4|5|6|7|1E|8|@$9|1F|A|1G|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|1H|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|1I|8|@]|D|@]|E|$]]|$1|M|3|N|5|H|7|1J|8|@]|D|@]|E|$I|J]]|$1|O|3|P|5|6|7|1K|8|@]|D|@]|E|$]]|$1|Q|3|R|5|H|7|1L|8|@]|D|@]|E|$I|J]]|$1|S|3|T|5|6|7|1M|8|@$9|1N|A|1O|B|C]|$9|1P|A|1Q|B|C]|$9|1R|A|1S|B|C]]|D|@]|E|$]]|$1|U|3|V|5|6|7|1T|8|@$9|1U|A|1V|B|C]]|D|@]|E|$]]|$1|W|3|X|5|H|7|1W|8|@]|D|@]|E|$I|J]]|$1|Y|3|Z|5|6|7|1X|8|@]|D|@]|E|$]]|$1|10|3|11|5|H|7|1Y|8|@]|D|@]|E|$I|J]]|$1|12|3|13|5|6|7|1Z|8|@$9|20|A|21|B|C]|$9|22|A|23|B|C]|$9|24|A|25|B|C]]|D|@]|E|$]]|$1|14|3|15|5|H|7|26|8|@]|D|@]|E|$I|J]]|$1|16|3|17|5|6|7|27|8|@$9|28|A|29|B|C]|$9|2A|A|2B|B|C]|$9|2C|A|2D|B|C]]|D|@]|E|$]]|$1|18|3|19|5|6|7|2E|8|@]|D|@]|E|$]]|$1|1A|3|1B|5|H|7|2F|8|@]|D|@]|E|$I|J]]|$1|1C|3|-4|5|6|7|2G|8|@]|D|@]|E|$]]]|1D|$]]

If you're stuck with pre-5.10, then the solutions provided above will not fully replicate the <code>say</code> function. For example

<pre><code>sub say { print @_, "\n"; }
</code></pre>

Will not work with invocations such as

<pre><code>say for @arr;
</code></pre>

or 

<pre><code>for (@arr) {
 say;
}
</code></pre>

... because the above function does not act on the implicit global <code>$_</code> like <code>print</code> and the real <code>say</code> function.

To more closely replicate the perl 5.10+ <code>say</code> you want this function

<pre><code>sub say {
 if (@_) { print @_, "\n"; }
 else { print $_, "\n"; }
}
</code></pre>

Which now acts like this

<pre><code>my @arr = qw( alpha beta gamma );
say @arr;
# OUTPUT
# alphabetagamma
#
say for @arr;
# OUTPUT
# alpha
# beta
# gamma
#
</code></pre>

The <code>say</code> builtin in perl6 behaves a little differently. Invoking it with <code>say @arr</code> or <code>@arr.say</code> will not just concatenate the array items, but instead prints them separated with the list separator. To replicate this in perl5 you would do this

<pre><code>sub say {
 if (@_) { print join($", @_) . "\n"; }
 else { print $_ . "\n"; }
}
</code></pre>

<code>$"</code> is the global list separator variable, or if you're using <code>English.pm</code> then is is <code>$LIST_SEPARATOR</code>

It will now act more like perl6, like so

<pre><code>say @arr;
# OUTPUT
# alpha beta gamma
#
</code></pre>

In Perl most of my <code>print</code> statements take the form

<pre><code>print "hello." . "\n";
</code></pre>

Is there a nice way to avoid keeping all the pesky "\n"s lying around?

I know I could make a new function such as <code>myprint</code> that automatically appends \n, but it would be nice if I could override the existing <code>print</code>.

How can Perl's print add a newline by default?

Perl

在Perl中，我的大多数print语句都采用以下形式print "hello." . "\n";有没有一种好的方法来避免把所有讨厌的“\n”都放在那里？我知道我可以创建一个新函数，比如自动追加\n的myprint，但是如果我可以覆盖现有的print，那就太好了。

问Perl的print如何在默认情况下添加换行符？
EN

回答 6

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问Perl的print如何在默认情况下添加换行符？EN

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