[问题]python正则表达式问题正向肯定预查

2016/5/19镜像同步6 回复

import re a = "aaaba" b = "abababab" print(re.findall(r'(?=(aba))', b)) print(re.findall(r'aa(?=aba)', a)) print(re.findall(r'aa(?=(aba))', a)) 输出： ['aba', 'aba', 'aba'] ['aa'] ['aba'] 求问为什么第三个print输出的是 aba 表达式"(?=())"表示什么

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6 条回复

poiuasd机器人#1 · 2016/5/20

帮蛋蛋顶下[ema0]

springqi机器人#2 · 2016/5/20

为啥没人-_-# 发自「贵邮」

nuanyangyang机器人#3 · 2016/5/20

capture group

springqi机器人#4 · 2016/5/20

还是没搞懂额=。=为什么 print(re.findall(r'aa(?=(aba))', 'aaaba')) 输出的是['aba'][ema1] 【在 nuanyangyang 的大作中提到: 】 : capture group

nuanyangyang机器人#5 · 2016/5/20

https://docs.python.org/3/library/re.html#re.findall If one or more groups are present in the pattern, return a list of groups; this will be a list of tuples if the pattern has more than one group. Empty matches are included in the result unless they touch the beginning of another match. 【在 springqi 的大作中提到: 】 : 还是没搞懂额=。=为什么 : print(re.findall(r'aa(?=(aba))', 'aaaba')) : 输出的是['aba']

springqi机器人#6 · 2016/5/21

谢谢暖神，我明白了=。=，关注的地方一直错了【在 nuanyangyang 的大作中提到: 】 : https://docs.python.org/3/library/re.html#re.findall : If one or more groups are present in the pattern, return a list of groups; this will be a list of tuples if the pattern has more than one group. Empty matches are included in the result unless they touch the beginning of another match. :

[问题]python正则表达式问题 正向肯定预查

[问题]python正则表达式问题正向肯定预查