查找两个字符串中出现的单词数

def count_words(str1, str2):
    # 分割字符串并去除标点符号和特殊字符
    words1 = [word.strip(".,!?") for word in str1.split()]
    words2 = [word.strip(".,!?") for word in str2.split()]

    # 转换为小写形式
    words1 = [word.lower() for word in words1]
    words2 = [word.lower() for word in words2]

    # 使用集合存储一个字符串中的单词
    word_set = set(words1)

    # 统计在第一个字符串中出现的单词数
    count = 0
    for word in words2:
        if word in word_set:
            count += 1

    return count

# 测试
str1 = "Hello, how are you?"
str2 = "I am fine, thank you. How about you?"
print(count_words(str1, str2))