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Python Regular Expressions in Python Introduction to Regular Expressions Negated Numbers

Marzoog AlGhazwi
Marzoog AlGhazwi
15,796 Points
Posted by Marzoog AlGhazwi
Marzoog AlGhazwi
15,796 Points

why it work with the '8' but with it didn't ??!

Can any one expline why its working that way !

negate.py 
import re

string = '1234567890'

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

1 Answer

Steven Parker
Steven Parker
229,732 Points
Steven Parker
Steven Parker
229,732 Points

The "\d" token matches any digit, so without the "8" you get two pieces, "1234" and then "7890" because it "7" is matched by the "\d".

But when you add "8" to the excluded digits, then "7890" no longer matches, so you get "890" where the "8" matches the "\d":.

A more conventional solution might use just one character class without the "any digit" preceding it.