Python 字符串加减运算实现：自定义类扩展字符串功能

class NewStr(str): def add(self, other): new_str = '' for char in other: if char not in self: new_str += char return self + new_str

def __sub__(self, other):
    new_str = ''
    for char in self:
        if char not in other:
            new_str += char
    return new_str

string1 = NewStr(input()) string2 = NewStr(input())

print(string1 + string2) print(string1 - string2)