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Python Regular Expressions in Python Introduction to Regular Expressions Negated Numbers

Negative Numbers Task Help


I cant work out why my reg ex is returning numbers in pairs, and misses off the zero at the end?

Please help :(

import re

string = '1234567890'

good_numbers = (re.findall(r"[\d][^5678]", string))

2 Answers

I was completely overthinking it, the solution was simply: good_numbers = (re.findall(r"[^567]", string))

Chris Freeman
Chris Freeman
Treehouse Moderator 68,423 Points

Glad you worked it out! Working through your original solution, the regex makes the following matches:

  • "12" since 2 is not in "5678"
  • "34" since 4 is not in "5678"
  • skips 5 since 6 is in "5678"
  • skips 6 since 7 is in "5678"
  • skips 7 since 8 is in "5678"
  • "89" since 9 is not in "5678"
  • "0" is skipped since there aren't any more characters in pattern