为什么 Perl 说全局符号“SYMBOL"?在 PROGRAM.pl 第 X 行需要明确的包名? [英] Why does Perl say Global symbol "SYMBOL" requires explicit package name at PROGRAM.pl line X?

问题描述

我正在用 Perl 编写我的第一个程序，并写道:

I´m writing my first programs in Perl, and wrote this:

use strict;
use warnings;
$animal = "camel";
print($animal);

当我运行它时，我从 Windows 命令行收到这些消息:

When I run it, I get these messages from the Windows command-line:

Global symbol "animal" requires explicit package name at stringanimal.pl line 3
Global symbol "animal" requires explicit package name at stringanimal.pl line 4

请问，有人知道这些消息是什么意思吗?

Please, could anyone what these messages mean?

推荐答案

use strict; 强制您在使用变量之前声明它们.如果您不这样做(如您的代码示例中所示)，您将收到该错误.

use strict; forces you to declare your variables before using them. If you don't (as in your code sample), you'll get that error.

要声明变量，请更改此行:

To declare your variable, change this line:

$animal = "camell";

致:

my $animal = "camell";

请参阅声明变量"以获得更深入的解释，以及use strict 的 Perldoc 部分.

See "Declaring variables" for a more in-depth explanation, and also the Perldoc section for use strict.

附言骆驼拼写为骆驼":-)

P.S. Camel is spelt "camel" :-)

错误信息的实际意思是 Perl 找不到名为 $animal 的变量，因为它没有被声明，并假设它必须是一个在包中定义的变量，但你忘记在它前面加上包名，例如$packageName::animal.显然，这里不是这种情况，您只是没有声明 $animal.

What the error message actually means is that Perl can't find a variable named $animal since it hasn't been declared, and assumes that it must be a variable defined in a package, but that you forgot to prefix it with the package name, e.g. $packageName::animal. Obviously, this isn't the case here, you simply hadn't declared $animal.

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