如果以非贪婪的方式使用python中的正则表达式中的量词{m，n}，那么第二个限制的用途是什么？

Question

The regular expression in Python re.compile(r'\\w{3,5}?') will match with any pattern that have at least three non-overlapping alpha-numeric and underscore characters. My question here 'is the second limit has any use in this non greedy use of quantifier {3,5}, ie even if the five is replaced by any other number the result would be same. ie re.compile(r'\\w{3,5}?')=re.compile(r'\\w{3,6}?')=re.compile(r'\\w{3,7}?')=re.compile(r'\\w{3,}?') Can some one give me an example where the second limit find any use?

Answer 1

When a lazily quantified pattern appears at the end of the pattern, it matches the minimum amount of chars it needs to match to return a value. A 123(\\w*?) will always yield no value inside Group 1 as *? matches zero or more chars, but as few as possible .

It means that \\w{3,5}? regex will always match 3 word chars, and the second argument will be "ignored" as it is enough to match 3 occurrences of the word char.

If the lazy pattern is not at the end, the second argument is important.

See an example: Test: (\\w{3,5}?)-(\\d+) captures different amount of chars in Group 1 depending on how match word chars there are in the strings.