'''
非高频特殊字符
'''
import re


# 单词边界
def s1():
    pattern = r"er\b"  # \b以什么结尾
    pattern = r"er\B"  # \B不以什么结尾
    print(re.search(pattern, "never"))
    print(re.search(pattern, "verb"))


# 其它特殊字符举例
def s2():
    print(re.match("(?i)abc", "ABC"), "(?i)忽略大小写")  # (?i)忽略大小写
    print(re.match("(?i)abc", "AbC"))
    print(re.match("(?i)abc(?#你妹我是注释)", "AbC"), "(?#)注释")  # (?#)注释
    print(re.match("a(?=bc)", "abc"), "(?=)等于")  # (?=)等于
    print(re.match("a(?=bc)", "a mother fucker"))
    print(re.match("a(?!bc)", "abc"), "(?!)不等于")  # (?!)不等于
    print(re.match("a(?!bc)", "mother a fucker"))
    print(re.search("(?<=bc)a", "bca"), "与(? =...)含义相同")
    print(re.search("(?<=bc)a", "fxa"))
    print(re.search("(?<!bc)a", "bca"), "与(?! ...)含义相同")
    print(re.search("(?<!bc)a", "fxa"))


if __name__ == "__main__":
    # s1()
    s2()