Regular Expression Puzzles and AI Coding Assistants

4 Creating functions using regexen

Very often in Python, or in other programming languages, you will want to wrap a regular expression in a small function rather than repeat it inline.

Puzzle 10    Reimplementing str.count()

Summary Create a function equivalent to str.count() using regular expressions.

The Python method str.count() is widely useful to find substrings inside a larger string. For example, here is some typical code you might write:

# Lyric from song "Hot Knife" by Fiona Apple
>>> s = """If I'm butter, if I'm butter
If I'm butter, then he's a hot knife
He makes my heart a CinemaScope screen
Showing the dancing bird of paradise
"""
>>> s.count('e')
15
>>> s.count('tt')
3

Imagine that Python did not have the method str.count() but ...