python定义一个复数类

以下是一个简单的Python复数类的定义：

class ComplexNumber:
    def __init__(self, real, imag):
        self.real = real
        self.imag = imag

    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):
        return ComplexNumber(self.real * other.real - self.imag * other.imag, self.real * other.imag + self.imag * other.real)

    def __truediv__(self, other):
        denominator = other.real**2 + other.imag**2
        return ComplexNumber((self.real * other.real + self.imag * other.imag)/denominator, (self.imag * other.real - self.real * other.imag)/denominator)

    def __str__(self):
        if self.imag >= 0:
            return f"{self.real} + {self.imag}i"
        else:
            return f"{self.real} - {-self.imag}i"

# 测试
a = ComplexNumber(3, 4)
b = ComplexNumber(2, -1)

print(a + b)  # 输出：5 + 3i
print(a - b)  # 输出：1 + 5i
print(a * b)  # 输出：(10 + 5i)
print(a / b)  # 输出：(0.4 + 1.8i)

以上的代码中，我们定义了一个名为ComplexNumber的类，它有两个属性：实部和虚部。我们还重载了加、减、乘、除和字符串表示方法，以便我们可以像使用内置类型一样使用这个自定义类型。