Find All Matches

re.findall() and re.finditer() walk the string returning every non-overlapping match.

Algorithm:

The max(m.end, i + 1) guard is important: if your pattern is .*, every position matches with length 0, so without the guard you'd loop forever.

re.split(pattern, text) is the inverse: cut the text at every match, return the pieces:

re.sub(pattern, repl, text) does findall + replace in one pass. Replacement strings can use \1, \2 to reference captures.