if __name__ == '__main__':

    import re

    string = 'cat like fish, rabbit like carrot.'

    sub_string = re.sub('like', 'hate', string, flags=re.I)

    print(sub_string)  # 输出：cat hate fish, rabbit hate carrot.

    search_string = re.search('like', string, flags=re.I)

    print(search_string)  # 输出：<_sre.SRE_Match object; span=(4, 8), match='like'>

    match_string1 = re.match('like', string, flags=re.I)

    match_string2 = re.match('.*(like).*', string, flags=re.I)

    match_string3 = re.match('cat', string, flags=re.I)

    match_string4 = re.match('.*(fish|carrot).*', string, flags=re.I).groups()

    print(match_string1)  # 输出：None

    print(match_string2)  # 输出：<_sre.SRE_Match object; span=(0, 34), match='cat like fish, rabbit like carrot.'>

    print(match_string3)  # 输出：<_sre.SRE_Match object; span=(0, 3), match='cat'>

    print(match_string4)  # 输出：('carrot',)

    find_string1 = re.findall('like', string, flags=re.I)

    find_string2 = re.findall('like|carrot', string, flags=re.I)

    print(find_string1)  # 输出：['like', 'like']

    print(find_string2)  # 输出：['like', 'like', 'carrot']

    print('End!')