python定义一个类实现复数，并用方法实现加减乘除

好的，下面是实现复数类的代码：

class ComplexNumber:
    def __init__(self, real, imag):
        self.real = real
        self.imag = imag
    
    def __str__(self):
        if self.imag >= 0:
            return f"{self.real} + {self.imag}i"
        else:
            return f"{self.real} - {-self.imag}i"
    
    def __add__(self, other):
        return ComplexNumber(self.real + other.real, self.imag + other.imag)
    
    def __sub__(self, other):
        return ComplexNumber(self.real - other.real, self.imag - other.imag)
    
    def __mul__(self, other):
        real = self.real * other.real - self.imag * other.imag
        imag = self.real * other.imag + self.imag * other.real
        return ComplexNumber(real, imag)
    
    def __truediv__(self, other):
        denominator = other.real**2 + other.imag**2
        real = (self.real * other.real + self.imag * other.imag) / denominator
        imag = (self.imag * other.real - self.real * other.imag) / denominator
        return ComplexNumber(real, imag)

上面的代码中，我们定义了一个复数类，包含了实部和虚部两个属性。同时，我们重载了`__str__`方法，使得打印对象时能够输出正常的复数形式。此外，我们还重载了加减乘除四个运算符，实现了复数的加减乘除。