我正在尝试制作一个程序来查找圆的面积，作为我在 python 中的第一个项目。有人知道我做错了什么吗？

Question

I have tried putting 3.14 in as a variable, and am not sure what is wrong. It always gives me the same error message:

Traceback (most recent call last):

  File "/Users/[REDACTED]/PycharmProjects/Pi/main.py", line 2, in <module>
    Mn = (n * n) * 3.14
TypeError: can't multiply sequence by non-int of type 'str'

The code I am using is:

n = input()

Mn = (n * n) * 3.14

print(Mn)

Answer 1

the input() in the first line will return a string so any value you are giving as input for example 5 will be stored in n as a string, you can check the type of n by using type(n).

instead use int(input()) this will store the input you pass as an integer; similarly for float input you can use float(input())

to fix your issue: make these changes:

n = int(input())

Mn = (n * n) * 3.14

print(Mn)

Answer 2

You are multiplying a string by a string. Use int(n) * int(n) or int(n) ** 2 .