Perl变量声明中的$、@、%有什么区别？

发布于 2024-10-30 16:28:58 字数 175 浏览 5 评论 0原文

示例：

my $some_variable;
my @some_variable;
my %some_variable;

我知道，@ 似乎是数组，$ 是基元，完全正确吗？ % 是做什么用的？

Example:

my $some_variable;
my @some_variable;
my %some_variable;

I know, @ seems to be for array, $ for primitive, is it totally right?
What is % for?

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赢得她心 2024-11-06 16:28:58

Perl 的优点之一是它带有内置手册。输入以下命令：

perldoc perlintro

并查看 Perl 变量类型 部分。您还可以通过 perldoc.perl.org 有关 Perl 变量的部分在线查看此内容。

快速概述：

$foo 是一个标量变量。它可以保存单个值，可以是字符串、数字等。
@foo 是一个数组。数组可以保存多个值。您可以使用索引访问这些值。例如 $foo[0] 是数组的第一个元素，$foo[1] 是数组的第二个元素，等等（数组通常从零开始））。
%foo 是一个哈希，这就像一个数组，因为它可以保存多个值，但哈希是键控数组。例如，我有一个名为 %password 的密码哈希。这是由用户名键入的，值是用户的密码。例如：
$password{Fred} = "剑鱼";
$password{贝蒂} = "秘密";
$user = "弗雷德";
print "用户 $user 的密码是 $password{$user}\n"; #打印出剑鱼
$用户=“贝蒂”;
print "用户$user的密码是$password{$user}\n"; #Prints out Secret

请注意，当您引用哈希或数组中的单个值时，您可以使用美元符号。对于初学者来说有点混乱。

我建议您购买骆驼书。 Llama 书是学习 Perl，是对该语言的出色介绍。

One of the nice things about Perl is that it comes with a built in manual. Type in the following command:

perldoc perlintro

and take a look at the section Perl variable types. You can also see this on line with the perldoc.perl.org section on Perl variables.

A quick overview:

$foo is a scalar variable. It can hold a single value which can be a string, numeric, etc.
@foo is an array. Arrays can hold multiple values. You can access these values using an index. For example $foo[0] is the first element of the array and $foo[1] is the second element of the array, etc. (Arrays usually start with zero).
%foo is a hash, this is like an array because it can hold more than one value, but hashes are keyed arrays. For example, I have a password hash called %password. This is keyed by the user name and the values are the user's password. For example:
$password{Fred} = "swordfish";
$password{Betty} = "secret";
$user = "Fred";
print "The Password for user $user is $password{$user}\n"; #Prints out Swordfish
$user = "Betty";
print "The Password for user $user is $password{$user}\n"; #Prints out secret