Python Regular Expression Pattern * Is Not Working as Expected

Regex Quantifiers in Python (trying to match a group)

The second & third regex allows the empty string '' to be matched.

re.search is merely returning the first match as documented: https://docs.python.org/3/library/re.html#re.search

python regex re.compile and re.search

You'll need another quantifier, namely a +:

import re

real_comp = re.compile(r'([0-9]+)')
print(real_comp.search('+123i').group())

Which yields

123

Otherwise the regex engine reports a match before the very first consumed char ( [0-9]* is always true).

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