功能不起作用，说它没有定义？

Question

我正在尝试使用此代码来计算面积成本。我正在使用函数选项，但它说 cost 没有定义，我确实定义了它。

def space():
    """ This function will calculate the area of floor, that needs 
    flooring. """
    
    # asking for variables
    length =int(input('Please enter the length of the room in meters: '))
    width =int(input('Please enter the width of the room in meters: '))
    
    area=length*width
    
    return area

def flooring():
    """This function will take the flooring chosen by the user and will
    return the cost of the square meter."""
    
    while True:
        # asking for variables
        opt=int(input('Please select type of flooring: '))
        if (opt>=1 and opt<=5):
            break
        
    if (opt==1):
        price=18.75
    ...        
        
    return price
    
def cost():
    """This will calculate the cost of the flooring, and other costs, and
    will display them, aligned."""
    print(price)
    matCost=area*price
    print("$",matCost)  

###
### MAIN PROGRAM
###

while True:
    ...
    
    space()
    print()
    
    print('Types of Flooring')
    print()
    print('                Cost per sq.m.')
    print('1. Low Pile Carpet     $18.75')
    ...
    
    flooring()
    print()
    cost()

错误说，但我认为我已经定义了它。使用 opt 的 if 语句，我以为我已经定义了。

Traceback (most recent call last):
  File"main.py", line 80 in <module>
    cost()
  File"main.py", line 52 in <module>
    print(price)
NameError: name 'price' is not defined

Answer 1

我想你只是忘了在def cost():上添加价格

def cost(price):
    """This will calculate the cost of the flooring, and other costs, and
    will display them, aligned."""
    print(price)
    matCost=area*price
    print("$",matCost)  

price_result = flooring()
cost(price_result)

Answer 2

因为 price 变量是在函数内部定义的，所以它不是全局的。 不要尝试直接调用价格变量，您必须调用返回所述价格变量的 floor 方法。

def cost():
    """This will calculate the cost of the flooring, and other costs, and will display them, aligned."""
    price = flooring()

    # The area variable is also not defined outside of the space method so it would be a good idea to add this as well.
    area = space()
    print(price)
    matCost=area*price
    print("$",matCost)

解决楼层类型重复询问问题：

在下面的代码块中，print(flooring()) 语句正在调用 floor 函数，因此，重新运行 input()

要解决此问题，您必须更改以下代码块： （阅读评论！）

while True:
    ...
    
    space()
    print()
    
    print('Types of Flooring')
    print()
    print('                Cost per sq.m.')
    print('1. Low Pile Carpet     $18.75')
    ...
    
    # Set price variable to the flooring() method the first time you call it!
    price = flooring()
    print()
    cost()

设置全局价格变量后，在函数中使用如图：

def cost():
    """This will calculate the cost of the flooring, and other costs, and
    will display them, aligned."""

    #using the global price variable
    print(price)
    matCost=space()*flooring()
    print("$",matCost)  

另外，如果您在意，请注意，当输入的地板类型不是 1 时，代码会引发错误，因此您可能想要打印类似“无效地板类型”之类的内容：

if (opt==1):
    price=18.75
else: 
    price="Invalid flooring type"