Test your knowledge: Python regular expressions

Review

1. Why are raw string literals usually recommended for patterns such as r"\d+"?

   Raw strings pass the backslashes more directly to the regular-expression engine; they do not change the regex matching rules.
2. Which operation should validate that an entire product code fits a pattern?

   fullmatch() succeeds only when the complete string matches the pattern.
3. In a pattern, what does [A-Z]{2} require?

   [A-Z] represents one uppercase Latin letter in this range, and {2} requires exactly two repetitions.
4. What is the purpose of a named group such as (?P<amount>\d+)?

   Named groups provide readable access through methods such as match.group("amount") or match.groupdict().
5. Why choose finditer() instead of findall() when reporting match positions?

   finditer() yields Match objects one at a time, including their source spans.
6. Which rule applies to Python regular-expression lookbehind assertions?

   Python requires lookbehind assertions to have fixed length, unlike lookahead assertions.