如何使用gsub替换为换行符？

Question

I have the following:

str = str.gsub(re, '<pre><code>\1</code></pre>'

Which outputs:

<pre><code>        stuff...

I would like for <pre><code> to be on its on line by itself. How can I insert a newline character there? If I enter \\n it shows up as HTML.

Answer 1

Newline characters need to be enclosed by double quotes. With double quotes you'll need an extra backslash for the pattern match:

str = str.gsub(re, "<pre><code>\n\\1\n</code></pre>"

Answer 2

String concatenation can help simplify the problem and avoid the leaning toothpick syndrome:

str = str.gsub(re, '<pre><code>\1</code></pre>'

Becomes:

str = str.gsub(re, "\n<pre><code>\n" + '\1' + "\n</code></pre>\n"

You can see what it's doing in IRB:

"\n<pre><code>\n" + '\1' + "\n</pre></code>\n"
=> "\n<pre><code>\n\\1\n</pre></code>\n"