python - 类型错误 : unsupported operand type(s) for -: 'str' and 'str' Simpleton

Question

这非常简单，到目前为止我发现的消息都没有处理我的低级问题，但这是我的代码。

name=input("What is your name?")
weight=input("How much do you weigh?")
target=input("What would you like to weigh?")
loss=weight-target
print("So...",name,'You need to lose',loss,"pounds!")
print("\n\nPress enter key to scram!")

错误:

Traceback (most recent call last):
  File "/Users/davebrown/Desktop/Pract.py", line 7, in <module>
    loss=weight-target
TypeError: unsupported operand type(s) for -: 'str' and 'str'

我不明白为什么它不受支持？

Answer 1

您不能减去 str 对象。 (与 Python 2.x 中的 input 不同，Python 3.x 中的 input 返回 str 对象)

>>> '2' - '1'
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: unsupported operand type(s) for -: 'str' and 'str'

将它们转换成int或 float首先。

>>> int('2') - int('1')
1