PHP正则表达式空间或换行符之前或之后

Question

I need to detect locations of start and end in several lines of pseudo code.

Basically, if the word "start" or the word "end" has a space or newline before and after, I need to record the match.

The space/newline recognition is important since start or end could be part of the contents that appears between start and end, ie

start
 start_time = 2
  end_time = 5
end

So far tried

preg_match('/((\s)|( *)(start)(\s)|( *))|((\s)|( *)(end)(\s)|( *))/i',
$line, $matches, PREG_OFFSET_CAPTURE);

...and variations.

Answer 1

You can use this regex to capture this block:

(?<= |\A)start(?=\s)[\s\S]*(?<=\s)end(?=\s|\z)

RegEx Demo