匹配包装图案

Question

What regex pattern can be used for finding word with a following dot that are in a parentheses pair.

as. df.kj hlasfa ( asd. las kdfh. ) dfs adk jfh. a (sd.kf) jhd (dsk fh. ) dskfdf asdf dfs lkjh asdfdsfjkhlkjh ( asdf. )as fadf asf

Desired results are bolded.

Answer 1

You could use a lookahead , that asserts that there is no opening parenthesis before the next closing one:

preg_match_all('/[a-zA-Z]+\.(?![a-zA-Z])(?=[^()]*\))/', $input, $matches);

You will find the four matches in $matches .

The first negative lookahead eliminates the case mentioned by HamZa in the comment. The second (positive) lookahead tries to find a closing parenthesis before the next opening one.

There is a caveat here. This will start to crumble once you have nested parentheses. some(text. (here)) would not match text. . Nested patterns (which can occur from using parentheses) are generally beyond the scope of regular expressions, although some engines can partly handle them. If this is the case for you, you are better of going through the string manually and counting parentheses.

Answer 2

许多选择之一是：

\b[a-zA-Z]+[.](?=[ )])(?=[^(]*[)])