CODEWITHSUNDEEP
pythonregex
CodyBugstein
CodyBugstein

Reputation: 23322

Matching both possible solutions in Regex

I have a string aaab. I want a Python expression to match aa, so I expect the regular expression to return aa and aa since there are two ways to find substrings of aa.

However, this is not what's happening.

THis is what I've done

a = "aaab"
b = re.match('aa', a)

Upvotes: 1

Views: 34

Answers (2)

CaHa
CaHa

Reputation: 1166

To generalize @stribizhev solution to match one or more of character a: (?=(a{1,}))

For three or more: (?=(a{3,})) etc.

Upvotes: 0

Wiktor Stribiżew
Wiktor Stribiżew

Reputation: 627101

You can achieve it with a look-ahead and a capturing group inside it:

(?=(a{2}))

Since a look-ahead does not move on to the next position in string, we can scan the same text many times thus enabling overlapping matches.

See demo

Python code:

import re
p = re.compile(r'(?=(a{2}))')
test_str = "aaab"
print(re.findall(p, test_str))

Upvotes: 1

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