Join (“ n”)不是加入换行符的方式吗？

我有一个数组。

[1,2,3,4]

我想要一个包含所有元素的字符串用换行符分隔。

但当我尝试 [1,2,3,4].join("\n")我得到

1\n2\n3\n4

我觉得有一个明显的答案，但我不能找到它！

110127 次浏览

小开

最佳答案

Yes, but if you print that string out it will have newlines in it:

irb(main):001:0> a = (1..4).to_a
=> [1, 2, 3, 4]
irb(main):002:0> a.join("\n")
=> "1\n2\n3\n4"
irb(main):003:0> puts a.join("\n")
1
2
3
4

So it does appear to achieve what you desire (?)

小开

Try this also:

puts (1..4).to_a * "\n"

小开

A subtle error that can occur here is to use single quotes instead of double. That also has the effect of rendering the newlines as \n. So

puts a.join("\n")   # correct

is not the same as

puts a.join('\n')   # incorrect

There is an excellent write up on why this is the case here.

小开

Just in case anyone searching for this functionality in ERB template then try this :

(1..5).to_a.join("<br>").html_safe

小开

How about this If you wanted to print each element on new line..

> a = [1, 2, 3, 4]
> a.each{|e| puts e}
1
2
3
4
=> [1, 2, 3, 4]

小开

You may not want to use html_safe, like ajay said, depending on context. Html safe can be a security issue. This depends on if the original input was actually html safe. HTML safe should not be called on input direct from a user and typically should be called before the view.

https://bibwild.wordpress.com/2013/12/19/you-never-want-to-call-html_safe-in-a-rails-template/

[edited in response to comment below]

小开

As some of the other answers above imply, Rails may be escaping your code before rendering as html. Here's a sample that addresses this problem (first sanitizing the inputs, so that you can "safely" call html_safe on the result):

my_array = [1, 2, 3, 4]
my_array.map{ |i| i.to_s.sanitize }.join("\n").html_safe

You only need sanitize if you don't trust the inputs.