For a larger Python program I am developing, I am trying to write a method which removes all sections of a string eveloped by two different tags; a start tag r'{foo}' and an end tag r'{/foo}'. If it were to run successfully, it would take a string such as:
r'stay {foo}leave{/foo} stay {foo} leave {/foo} stay'
and return string:
r'stay stay stay'.
Furthermore, it wouldn’t do anything if the sections were incomplete. In other words, if you gave the program string:
r'stay {/foo} {foo} leave {/foo} {foo} stay'
it would return string:
r'stay {/foo} {foo} stay'
which is the intended behavior.
To resolve this issue, I turned to the python re library to create a regular expression that would do this for me. The closest thing I’ve had to success is with the regex pattern r'{foo}.*{/foo}' which only works, if and only if, there is one tagged section within the string. For example, using the pattern r'{foo}.*{/foo}' with string:
r'stay {foo} leave {/foo} stay'
would return r'stay stay' as expected, but if I do the same with the first example:
r'stay {foo}leave{/foo} stay {foo} leave {/foo} stay'
I’d get r'stay stay' instead of the expected result r'stay stay stay'.
While I feel like I am so close to figuring this out, my understanding of regular expressions is far from advanced. I would appreciate some help troubleshooting the right regex pattern for this scenario.
>Solution :
Use the "non-greedy" (a.k.a. "minimal") version of the star operator, which is *?. Reference: https://docs.python.org/3/library/re.html#regular-expression-syntax
Hence, change your pattern to: r'{foo}.*?{/foo}'