如何检查某些字符是否不在字符串中？

Question

import os
class Converter(object):
def dec_to_any(self, a, b):
    self.values = {0: "0", 1: "1", 2: "2", 3: "3", 4: "4", 5: "5", 6: "6", 7: "7", 8: "8", 9: "9", 10: "A", 11: "B", 12: "C", 13: "D", 14: "E", 15: "F", 16: "G", 17: "H", 18: "I", 19: "J", 20: "K", 21: "L", 22: "M", 23: "N", 24: "O", 25: "P", 26: "Q", 27: "R", 28: "S", 29: "T", 30: "U", 31: "V"}
    self.universal = []
    self.temp_uni = []
    while a != 0:
        if a < b:
            self.universal.append(self.values.get(a, "unavailable"))
            a -= a
        else:
            self.universal.append(self.values.get((a % b), "unavailable"))
            a //= b
    for i in range(len(self.universal) + 1):
        self.temp_uni.append(self.universal[-i])
    del self.temp_uni[0]
    self.universal = ""
    for i in self.temp_uni:
        self.universal += str(i)
    return self.universal
def any_to_dec(self, a, b):
    a = int(a, b) #problem part 3 start and end
    return a
def display(self):
    print("Hello and welcome to the base converternHere is the menu:nt0 - closent1 - convertnn")
def main(self):
    while True:
        try:
            self.display()
            self.option = int(input("Please select one: "))
            while self.option > 1 or self.option < 0:
                os.system("cls")
                self.display()
                self.option = int(input("Please select one: "))
            os.system("cls")
            break
        except:
            os.system("cls")
            pass
    if self.option == 1:
        while True:
            try:
                self.base1 = int(input("Please enter a base to convert from (2-32): "))
                while self.base1 < 2 or self.base1 > 33:
                    os.system("cls")
                    self.base1 = int(input("Please enter a base to convert from (2-32): "))
                break
            except:
                os.system("cls")
                pass
        while True:
            try:
                self.number = str(input("Please enter a number to convert: ")).upper()
                break
            except:
                os.system("cls")
                pass
        while True: #problem part 1 start
            try:
                self.base2 = int(input("Please enter a base to convert to (2-36): "))
                while self.base2 < 2 or self.base2 > 37:
                    os.system("cls")
                    self.base2 = int(input("Please enter a base to convert to (2-36): "))
                break
            except:
                os.system("cls")
                pass #problem part 1 end
        os.system("cls")
        self.return_val = self.any_to_dec(self.number, self.base1) #problem part 2 start and end
        self.return_val = self.dec_to_any(self.return_val, self.base2)
        print(self.number, "in base", self.base1, "would be", 
self.return_val, "in base", self.base2)
start = Converter()
start.main()

这是代码，供参考。我正在制作一个基本转换器，用户在其中选择一个基础要转换到并输入一个数字，转换器吐出了转换的数字。我的困境是，用户可以输入基本2，并超过他们输入的最终呈现错误，我试图通过添加if语句来检查他们所在的基础，并且wier thile loop loop说，不要继续进行，直到没有引起字符的错误。但这很筋疲力尽。是否有一种自动化的方法可以做？喜欢：

base_2 = ["0", "1"]

如果出现了任何不在 base_2中的东西：

  some prevention code....

Answer 1

在我的评论中扩展，您可以从string模块中获取数字和字母。以下是针对基本1-36的案例不敏感的文字。

from string import digits, ascii_lowercase
characters = digits + ascii_lowercase

def is_valid(literal, base):
    valid_digits = characters[:base]
    return set(valid_digits).issuperset(literal.lower())

is_valid('01010101', 2)
# True
is_valid('100101a', 2)
# False
is_valid('DeadBeef', 16)
# True
is_valid('123z', 16)
# False