从索引到字符串结尾的子字符串的 Ruby 习语
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Ruby idiom for substring from index until end of string
提问by Sherwin Yu
Just wondering if there's a Ruby idiom for extracting a substring from an index until the end of the string. I know of str[index..-1]which works by passing in a range object to the String's []method but it's a little clunky. In python, for example, you could write str[index:]which would implicitly get you the rest of the string.
只是想知道是否有用于从索引中提取子字符串直到字符串末尾的 Ruby 习惯用法。我知道str[index..-1]通过将 range 对象传递给String's[]方法可以工作，但它有点笨拙。例如，在 python 中，您可以编写str[index:]which 将隐式地获取字符串的其余部分。
Example:
例子：
s = "hello world"
s[6..-1] # <-- "world"
Is there anything nicer than s[6..-1]?
有比 更好的s[6..-1]吗？
采纳答案by Paul Brit
I think it isn't.
我认为不是。
It seems that Rangeis better way to do it.
似乎这Range是更好的方法。
回答by Yevgeniy Anfilofyev
Here is 'nicer' if you wish. You can extend ruby String class and then use this method into your code. For example:
如果您愿意，这里是“更好”。您可以扩展 ruby String 类，然后在您的代码中使用此方法。例如：
class String
def last num
self[-num..-1]
end
end
And then:
进而：
s = "hello world"
p s.last(6)
回答by Simon Tsang
To get the string from a range:
要从范围中获取字符串：
s = 'hello world'
s[5..s.length - 1] # world
However, if you just want to get the last word:
但是，如果您只想获得最后一句话：
'hello world'.split(' ').last # world
回答by vicentazo
Ruby 2.6 introduced endless ranges, which basically remove the need to have to specify the end index. In your case, you can do:
Ruby 2.6 引入了无穷范围，这基本上消除了必须指定结束索引的需要。在你的情况下，你可以这样做：
s = "hello world"
s[6..]
回答by Flauwekeul
You can extend the Stringclass. Not sure if it's a ruby idiom though:
您可以扩展String该类。不确定它是否是 ruby 习语：
class String
def last(n)
self[(self.length - n)..-1]
end
end
回答by MothOnMars
Rails' activesupportlibrary (which can be installed as a gem independent of Rails) adds a frommethod to strings:
Rails 的activesupport库（可以作为独立于 Rails 的 gem 安装）from为字符串添加了一个方法：
> s = "hello world"
"hello world"
> s.from(6)
"world"
https://api.rubyonrails.org/classes/String.html#method-i-from
https://api.rubyonrails.org/classes/String.html#method-i-from
