I'm trying to write a regex to match the pattern (##a.+?#a##b.+?#b) in strings where it might appear more than one time:

foo##abar#a##bfoo#bbar##afoo#a##bbar#bfoobar

What I would like to do is to substitute the whole string with just the pattern, so I've tried the following using regex101 (python flavor):

Regex:

.*?(##a.+?#a##b.+?#b).*?

The problem is that, if the last occurrence of the pattern is followed by some text, as in the example above, the last portion is not matched, giving:

##abar#a##bfoo#b##afoo#a##bbar#bfoobar 

Expected output:

##abar#a##bfoo#b##afoo#a##bbar#b (just the matched pattern w/out extra text)

Is there a workaround for this kind of task? Many thanks in advance for any suggestion.

I'm trying to write a regex to match the pattern (##a.+?#a##b.+?#b) in strings where it might appear more than one time:

foo##abar#a##bfoo#bbar##afoo#a##bbar#bfoobar

What I would like to do is to substitute the whole string with just the pattern, so I've tried the following using regex101 (python flavor):

Regex:

.*?(##a.+?#a##b.+?#b).*?

The problem is that, if the last occurrence of the pattern is followed by some text, as in the example above, the last portion is not matched, giving:

##abar#a##bfoo#b##afoo#a##bbar#bfoobar 

Expected output:

##abar#a##bfoo#b##afoo#a##bbar#b (just the matched pattern w/out extra text)

Is there a workaround for this kind of task? Many thanks in advance for any suggestion.

• python
• regex

• Unclear? Can you add real samples? – aaa Commented Feb 3 at 18:24
• What's the expected output? I don't understand what "substitute the whole string with just the pattern" means. – Fravadona Commented Feb 3 at 18:33
• Just extract the matches and concat them. What is the programming language? – Wiktor Stribiżew Commented Feb 3 at 18:42
• Yes @trincot, that did it, thank you very much! – eazyezy Commented Feb 3 at 21:30

1 Answer 1

You could add |$ in the group and then only match other characters before the group. That way you solve the issue of not getting rid of the suffix:

.*?(##a.+?#a##b.+?#b|$)

See it on regex101