你好，我是悦创。

我的一个一对一学员的提问：

问题代码：

import re

def roman_numerals(text):
    """
    Finds any string of letters that could be a Roman numeral
    (made up of the letters I, V, X, L, C, D, M).

    >>> roman_numerals("Sir Richard IIV, can you tell Richard VI that Richard IV is on the phone?")
    ['IIV', 'VI', 'IV']
    >>> roman_numerals("My TODOs: I. Groceries II. Learn how to count in Roman IV. Profit")
    ['I', 'II', 'IV']
    >>> roman_numerals("I. Act 1 II. Act 2 III. Act 3 IV. Act 4 V. Act 5")
    ['I', 'II', 'III', 'IV', 'V']
    >>> roman_numerals("Let's play Civ VII")
    ['VII']
    >>> roman_numerals("i love vi so much more than emacs.")
    []
    >>> roman_numerals("she loves ALL editors equally.")
    []
    """
    return re.findall(__________, text)

最后写出如下正则表达式：

\b[IVXLCDM]+\b

import re


def roman_numerals(text):
	"""
	Finds any string of letters that could be a Roman numeral
	(made up of the letters I, V, X, L, C, D, M).

	# >>> roman_numerals("Sir Richard IIV, can you tell Richard VI that Richard IV is on the phone?")
	['IIV', 'VI', 'IV']
	# >>> roman_numerals("My TODOs: I. Groceries II. Learn how to count in Roman IV. Profit")
	['I', 'II', 'IV']
	# >>> roman_numerals("I. Act 1 II. Act 2 III. Act 3 IV. Act 4 V. Act 5")
	['I', 'II', 'III', 'IV', 'V']
	# >>> roman_numerals("Let's play Civ VII")
	['VII']
	# >>> roman_numerals("i love vi so much more than emacs.")
	[]
	# >>> roman_numerals("she loves ALL editors equally.")
	[]
	"""
	pattern = r"\b[IVXLCDM]+\b"
	return re.findall(pattern, text)


if __name__ == '__main__':
	while True:
		a = roman_numerals(input(">>>"))
		print(a)

加循环是为了方便测试

>>>Sir Richard IIV, can you tell Richard VI that Richard IV is on the phone?
['IIV', 'VI', 'IV']
>>>My TODOs: I. Groceries II. Learn how to count in Roman IV. Profit
['I', 'II', 'IV']
>>>I. Act 1 II. Act 2 III. Act 3 IV. Act 4 V. Act 5Let's play Civ VII
['I', 'II', 'III', 'IV', 'V']
>>>Let's play Civ VII
['VII']
>>>i love vi so much more than emacs.
[]
>>>she loves ALL editors equally.
[]
>>>

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