Question

我正在尝试学习如何创建函数。如何将此代码更改为多个函数？

purchase = input('Enter the amount of purchase: ')
statetaxes = purchase * 0.05
countytaxes = purchase * 0.025
totaltaxes = (statetaxes + countytaxes)
totalPurchase = (purchase + totaltaxes)

print('The amount of purchase is $'), format(purchase, ',.2f')
print('State tax: $'), format(statetaxes, ',.2f')
print('County tax: $'), format(countytaxes, ',.2f')
print('Total tax: $'), format(totaltaxes, ',.2f')
print('Total: $'), format(totalPurchase, ',.2f')

会是这样的：

def main():

    purchase = get_purchase
    statetaxes = get_state
    countytaxes = get_county
    totaltaxes = statetaxes + countytaxes
    totalPurchase = totaltaxes + purchase

    print('The amount of purchase is $', purchase)
    print('State tax: ', statetaxes)
    print('County tax: ', countytaxes)
    print('Total tax: ', totaltaxes)
    print('Total: $'. totalPurchase)

def get_purchase():
    purchase = float(input('Please enter the amount of purchase')
    return purchase

def get_state():
    state = purchase * 0.05
    return statetaxes

def get_county():
    countytaxes = purchase * 0.025
    return countytaxes

main()

这是对的吗？如果没有，我哪里错了？

我这样做没有python翻译，因为我现在正在使用平板电脑等待航班。

编辑：我要做的是将顶级程序分成多个功能。当我输入此代码时：

def get_purchase():
    return float(input('Please enter the amount of purchase '))

def get_state():
    return purchase * 0.05


def get_county():
    return purchase * 0.025

def main():

    purchase = get_purchase()
    statetaxes = get_state()
    countytaxes = get_county()
    totaltaxes = statetaxes + countytaxes
    totalPurchase = totaltaxes + purchase

    print('The amount of purchase is $', purchase)
    print('State tax: ', statetaxes)
    print('County tax: ', countytaxes)
    print('Total tax: ', totaltaxes)
    print('Total: $'. totalPurchase)

main()

我收到此错误：

Please enter the amount of purchase 5000
Traceback (most recent call last):
  File "salestax.py", line 49, in <module>
    main()
  File "salestax.py", line 38, in main
    statetaxes = get_state()
  File "salestax.py", line 27, in get_state
    return purchase * 0.05
NameError: name 'purchase' is not defined

我现在坐飞机，但会在停留时检查，看看我做错了什么。

Answer 1

您需要调用您的函数，方法是添加左/右括号：

purchase = get_purchase()

在get_state()中，您有state和statetaxes个变量 - 您只想使用其中一个。

此外，作为mhawke mentioned，您需要get_state和get_county获取purchase参数，传递从主要商品购买在你打电话时起作用。

除此之外，您的功能似乎正确地分离了逻辑操作。

Answer 2

代码审核：

将main（）代码移到底部。

def get_purchase(): 
    '''Use docstrings to describe the function'''
    # purchase = float(input('Please enter the amount of purchase')
    # return purchase # no need to assign and then return the assignment
    # just return what you'd otherwise assign:
    return float(input('Please enter the amount of purchase')) # was missing a )

def get_state():
    '''calculate and return state taxes'''
    # state = purchase * 0.05
    # return statetaxes # see a problem here? what is statetaxes?
    return purchase * 0.05 # there, it's fixed!

def get_county():
    # countytaxes = purchase * 0.025
    # return countytaxes
    return purchase * 0.025

所以我们将你的main（）移到了底部。

def main():

    purchase = get_purchase() # now we're calling these with the ()'s
    statetaxes = get_state()
    countytaxes = get_county()
    totaltaxes = statetaxes + countytaxes
    totalPurchase = totaltaxes + purchase

    print('The amount of purchase is $', purchase)
    print('State tax: ', statetaxes)
    print('County tax: ', countytaxes)
    print('Total tax: ', totaltaxes)
    print('Total: $'. totalPurchase)

最后，在模块的底部，不要只是调用main()，使用常见的Python习语：

if __name__ == '__main__':
    main()

如果导入模块，它会阻止代码执行main（）。导入模块时，其__name__不再是'__main__'相关：What does if __name__ == "__main__": do?

Answer 3

这个答案是在您编辑的地方进行的，您已经更改了代码并且现在正在获得运行时异常。

函数def get_state()和get_county()都引用名为purchase的变量，该变量不在函数范围内。

您应该将purchase传递给每个函数，如下所示：

def get_state(purchase):
    return purchase * 0.05

def get_county(purchase):
    return purchase * 0.025

def main():
    purchase = get_purchase()
    statetaxes = get_state(purchase)
    countytaxes = get_county(purchase)

还有其他方法可以做到这一点，例如：基于类的方法，但是当你说你正在学习函数时，这可能是要走的路。

程序转换功能

3 个答案: