定义一个表示矩形（Juxing）的类,在类中定义矩形的两个属性：长（chang）和宽（kuan），分别用不同的构造函数实例化3个对象，并在控制台输出他们的周长和面积

class Juxing:
def __init__(self, chang, kuan):
self.chang = chang
self.kuan = kuan

def zhouchang(self):
return 2 * (self.chang + self.kuan)

def mianji(self):
return self.chang * self.kuan

jx1 = Juxing(3, 4)
jx2 = Juxing(5, 6)
jx3 = Juxing(7, 8)

print("jx1的周长为：", jx1.zhouchang(), "，面积为：", jx1.mianji())
print("jx2的周长为：", jx2.zhouchang(), "，面积为：", jx2.mianji())
print("jx3的周长为：", jx3.zhouchang(), "，面积为：", jx3.mianji())