用正則表達式匹配字符串

Question

我正在嘗試創建一個 function 來訪問，如果用戶輸入的用戶名與正則表達式匹配。 這是我的代碼：

def regular_expression():
    rules = "[A-Z]^{1}[a-zA-Z0-9]+[0-9]$"

    while True:
        username = str(input("Username Must have:\n"
                             "- First character must be an upper case letter\n"
                             " - Middle can be any letter or number\n"
                             "- Last character must be a number\n"
                             "> "
                             ))

        if re.fullmatch(rules, username):
            print("Accepted")

這是我收到的錯誤：

    return _compile(pattern, flags).fullmatch(string)
    p = sre_compile.compile(pattern, flags)
    p = sre_parse.parse(p, flags)
    p = _parse_sub(source, pattern, flags & SRE_FLAG_VERBOSE, 0)
    source.tell() - here + len(this))
re.error: multiple repeat at position 9

Answer 1

問題是“^{1}”在你的“規則”變量中，它的目的是什么？

我設法用這個來完成這項工作：

def regular_expression():
    rules = "^[A-Z][a-zA-Z0-9]+[0-9]$"

while True:
    username = str(input("Username Must have:\n"
                         "- First character must be an upper case letter\n"
                         " - Middle can be any letter or number\n"
                         "- Last character must be a number\n"
                         "> "
                         ))

    if re.fullmatch(rules, username):
        print("Accepted")
        break

*不要忘記添加'break'，退出循環；）