Today, I found out that regex r"['a', 'b']" matches 'a, b'.
Why is that? What does comma and ' mean inside []?
Thank you.
Asked
Active
Viewed 57 times
0
Paul R
- 2,631
- 3
- 38
- 72
-
Can we see the implementation of the regex? – Eli Sadoff Nov 07 '16 at 15:39
-
Have you tried reading the documentation https://docs.python.org/2/library/re.html ? – Tom Dalton Nov 07 '16 at 15:39
-
12`['a', 'b']` is the same as `[',ab]` – Patrick Haugh Nov 07 '16 at 15:39
-
Possible duplicate of [Reference - What does this regex mean?](http://stackoverflow.com/questions/22937618/reference-what-does-this-regex-mean) – coder Nov 07 '16 at 15:53
1 Answers
2
[] is used to define character sets in regular expressions. The expression will match if the string contains any of the characters in that set.
Your regular expression:
r"['a', 'b']"
Says "match if string contains ' or a or , or b. As @Patrick Haugh mentions in his comment. Your expression is equivalent to [',ab]. Repeating the same character in the set does nothing.
http://www.regexpal.com/ is a great site for testing your regular expressions. It can help break it down for you and explain what your expression does and why it matches on certain strings.
TheF1rstPancake
- 2,318
- 17
- 17