Perl `split` 不会`split` 到默认数组 [英] Perl `split` does not `split` to default array
问题描述
我对 split
有一个奇怪的问题,因为它默认不会 split
到默认数组中.
I have this strange problem with split
in that it does not by default split
into the default array.
下面是一些玩具代码.
#!/usr/bin/perl
$A="A:B:C:D";
split (":",$A);
print $_[0];
这不会打印任何内容.但是,如果我显式地拆分为像
This does not print anything. However if I explicitly split into the default array like
#!/usr/bin/perl
$A="A:B:C:D";
@_=split (":",$A);
print $_[0];
正确打印 A.我的 perl 版本是 v5.22.1.
It's correctly prints A. My perl version is v5.22.1.
推荐答案
split
默认不去@_
.@_
不像 $_
那样工作.它仅用于函数的参数.perlvar 说:
split
does not go to @_
by default. @_
does not work like $_
. It's only for arguments to a function. perlvar says:
在子例程中,数组@_ 包含传递给该子例程的参数.在子例程中,@_ 是数组运算符 pop 和 shift 的默认数组.
Within a subroutine the array @_ contains the parameters passed to that subroutine. Inside a subroutine, @_ is the default array for the array operators pop and shift.
如果你使用 use strict
和 use warnings
运行你的程序,你会看到
If you run your program with use strict
and use warnings
you'll see
然而,如果没有提供任何内容,split
确实使用 $_
作为它的第二个参数(被拆分的字符串).但是您必须始终使用返回值.
However, split
does use $_
as its second argument (the string that is split up) if nothing is supplied. But you must always use the return value for something.
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