regex-lookarounds - 意外的\ W？ 正则表达式环顾的行为(Unexpected W? behavior with regex lookaround)

Question

In a simple regex I want to match segments where "1 is not followed by 'a', possibly preceded by whitespaces", '1' may be followed by a nonword character (such as ",").

(在一个简单的正则表达式中，我要匹配以下段：“ 1后面不跟'a'，可能后面跟空格”，'1'后面跟一个非单词字符（例如“，”）。)

1\W(?!\s a) functions correctly (on test strings "1 a" and "1, a") 1\W?(?!\s a) does not function correctly.

(1 \ W（？！\ s a）正常运行（在测试字符串“ 1 a”和“ 1，a”上）1 \ W？（？！\ s a）正常运行。)

What is the explanation for this?

(这有什么解释？)

  ask by TonyR translate from so

Answer 1

等待大神答复