function - 函数中不支持的操作数类型

Question

4. 编写一个 Python 程序，它接受用户的圆半径并计算面积。转到编辑器示例输出：r = 1.1 面积 = 3.8013271108436504

我的代码：

def rad_to_area(rad):
    from math import pi
    area = pi * (rad**2)
    return area
radius = input('Enter radius of circle: ')
print('The area of the circle is', rad_to_area(radius))

错误：

Traceback (most recent call last):
  File "/tmp/sessions/167965d8c6c342dd/main.py", line 6, in <module>
    print('The area of the circle is', rad_to_area(radius))
  File "/tmp/sessions/167965d8c6c342dd/main.py", line 3, in rad_to_area
    area = pi * (rad**2)
TypeError: unsupported operand type(s) for ** or pow(): 'str' and 'int'

有人可以解释我做错了什么吗？

谢谢

Answer 1

该input方法是一个字符串，要对半径进行幂运算，您需要先将其转换为浮点数。

def rad_to_area(rad):
    from math import pi
    area = pi * (rad**2)
    return area
radius = float(input('Enter radius of circle: ')) #Casting as a float here
print('The area of the circle is', rad_to_area(radius))