Python自定义字符串类实现加减法运算

class MyStr(str): def add(self, other): res = self for c in other: if c not in self: res += c return res

def __sub__(self, other):
    res = ""
    for c in self:
        if c not in other:
            res += c
    return res

s1 = MyStr('abcdefg') s2 = MyStr('acdi') print(s1 + s2) # 'abcdefgi' print(s1 - s2) # 'bcef'