仅替换多个新行

Question

I am trying to do something kind of unusual. I want to replace multiple new lines with two new lines. There are plenty of questions like that but not exactly, see:

Hello\\n\\n\\nWorld\\n\\n\\n\\n!

Should become

Hello\\n\\nWorld\\n\\n!

This however

Hello\\nWorld\\n!

Should stay the same. The problem with my regex is that it replaces single new lines with two.

preg_replace('"(\\r?\\n)+"', "\\n\\n", $somevar)

Answer 1

这样的事情？

preg_replace('"(\r?\n){2,}"', "\n\n", $somevar)