Regular Expressions

Core functions

re.search finds a pattern anywhere in a string; re.findall returns every match; re.sub replaces matches.

import re

text = "Call 9876543210 or 8123456789"
phones = re.findall(r"\d{10}", text)
print(phones)                            # ['9876543210', '8123456789']

masked = re.sub(r"\d{10}", "[hidden]", text)
print(masked)

Common pattern pieces

\d digit, \w word char, \s whitespace, + one-or-more, * zero-or-more, ? optional. Prefix patterns with r"..." to avoid backslash headaches.