用Python定义一个可以计算圆、三角形、长方形、面积和周长的类

好的，以下是一个可以计算圆、三角形、长方形面积和周长的类，代码如下：

import math

class Shape:
    def __init__(self):
        self.area = 0
        self.perimeter = 0

    def calculate_area(self):
        pass

    def calculate_perimeter(self):
        pass

class Circle(Shape):
    def __init__(self, radius):
        super().__init__()
        self.radius = radius

    def calculate_area(self):
        self.area = math.pi * self.radius ** 2

    def calculate_perimeter(self):
        self.perimeter = 2 * math.pi * self.radius

class Triangle(Shape):
    def __init__(self, a, b, c):
        super().__init__()
        self.a = a
        self.b = b
        self.c = c

    def calculate_area(self):
        s = (self.a + self.b + self.c) / 2
        self.area = math.sqrt(s * (s - self.a) * (s - self.b) * (s - self.c))

    def calculate_perimeter(self):
        self.perimeter = self.a + self.b + self.c

class Rectangle(Shape):
    def __init__(self, width, height):
        super().__init__()
        self.width = width
        self.height = height

    def calculate_area(self):
        self.area = self.width * self.height

    def calculate_perimeter(self):
        self.perimeter = 2 * (self.width + self.height)

使用方法：

# 计算圆的面积和周长
circle = Circle(5)
circle.calculate_area()
circle.calculate_perimeter()
print("Circle area:", circle.area)
print("Circle perimeter:", circle.perimeter)

# 计算三角形的面积和周长
triangle = Triangle(3, 4, 5)
triangle.calculate_area()
triangle.calculate_perimeter()
print("Triangle area:", triangle.area)
print("Triangle perimeter:", triangle.perimeter)

# 计算长方形的面积和周长
rectangle = Rectangle(2, 4)
rectangle.calculate_area()
rectangle.calculate_perimeter()
print("Rectangle area:", rectangle.area)
print("Rectangle perimeter:", rectangle.perimeter)

输出结果：

Circle area: 78.53981633974483
Circle perimeter: 31.41592653589793
Triangle area: 6.0
Triangle perimeter: 12
Rectangle area: 8
Rectangle perimeter: 12