Ruby 中的 $_[0] ,$_[1] 是什么? [英] What is $_[0] ,$_[1] in Ruby?

问题描述

我是一名 Java 开发人员，我已经获得了 Ruby 代码以供理解并在以后继续工作.

I am a Java developer, and I have been given Ruby code to understand and later to work on.

我浏览了 tutorialspoint.com 上的 Ruby 教程，但我不知道 $_[0] 是什么.

I went through the Ruby tutorials on tutorialspoint.com but I can't figure out what $_[0] is.

它被分配给代码中的一个变量，它绝对不是命令行参数，因为我编写了代码来测试它并且失败了.那么，谁能说说它的意义是什么?

It is being assigned to a variable in the code, and it is definitely not a command-line argument because I wrote code to test that and it failed. So, can anyone say what the significance of it is?

推荐答案

这是神奇的变量之一.

$_ 保存从标准输入读取的最后一行的值.因此，$_[0] 是该字符串的第一个符号.

$_ holds value of the last line read from standard input. $_[0] is, therefore, first symbol of that string.

更多魔法变量见English.rb

# The last line read by <tt>Kernel.gets</tt> or
# <tt>Kernel.readline</tt>. Many string-related functions in the
# +Kernel+ module operate on <tt>$_</tt> by default. The variable is
# local to the current scope. Thread local.
alias $LAST_READ_LINE          $_

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