定义一个矩形类rectangle，无参构造函数设置length和width为0，有参构造函数设置对应length和width的形参值计算矩形周长，面积，输出矩形尺寸

class Rectangle:
def __init__(self, length=0, width=0):
self.length = length
self.width = width

def perimeter(self):
return 2 * (self.length + self.width)

def area(self):
return self.length * self.width

def display(self):
print(f"矩形尺寸为：{self.length} × {self.width}")

# 示例
r1 = Rectangle()
print("矩形1：")
r1.display()
print(f"周长：{r1.perimeter()}，面积：{r1.area()}")

r2 = Rectangle(3, 4)
print("矩形2：")
r2.display()
print(f"周长：{r2.perimeter()}，面积：{r2.area()}")