Python 如何在另一个子例程中使用来自子例程的输入

Question

我在 Python 中有一个问题要解决，即用户输入他们想要购买的商品数量等变量。我将其作为 def customer，输出为 'how many widgets would you like'，然后他们的输入乘以 10 英镑的价格。这一点工作正常。

我想将他们的输入带到另一个子例程中进行进一步的数学运算，例如税收和总计。是否有一些关键字供我研究以便我可以执行此操作？

到目前为止，这是我的代码：

def wall_1():
   height = int(input("Enter the height in metres of wall 1 : "))
   width = int(input("Enter the width in metres of wall 1 : "))
   wall_1_price = height * width
   price_all_walls(wall_1_price)
def wall_2():
   height = int(input("Enter the height in metres of wall 2 : "))
   width = int(input("Enter the width in metres of wall 2 : "))
   wall_2_price = height * width
   price_all_walls(wall_2_price)
def wall_3():
   height = int(input("Enter the height in metres of wall 3 : "))
   width = int(input("Enter the width in metres of wall 3 : "))
   wall_3_price = height * width
   price_all_walls(wall_3_price)
def wall_4():
   height = int(input("Enter the height in metres of wall 4 : "))
   width = int(input("Enter the width in metres of wall 4 : "))
   wall_4_price = height * width
   price_all_walls(wall_4_price)
def price_all_walls(wall_1_price, wall_2_price, wall_3_price, wall_4_price): 
   print("The total price so far is : " + 
       str(wall_1_price + wall_2_price + wall_3_price + wall_4_price))


if __name__ == "__main__":

   wall_1()
   wall_2()
   wall_3()
   wall_4()
   price_all_walls()

Answer 1

我不确定我是否正确理解了你的问题，但这可能会有所帮助。

def customer():
   number_items = int(input("Enter the number of items to buy : "))
   print("Widgets that you would like : £" + str(number_items * 10))
   total_price = number_items * 10
   further_maths(number_items, total_price) # Call to another subroutine further_maths with parameters number_items and total_price

def further_maths(number_items, total_price): # Subroutine definition
   print("The total number of items in another subroutine : " + str(number_items))
   print("The total price in another subroutine : " + str(total_price))

if __name__ == "__main__":
   customer()

在此代码中，子例程 customer() 中的参数被传递到另一个子例程 further_maths()。

Answer 2

此代码示例将解决您的问题。 price_all_walls 方法接受四个参数。在您的 wall_1()、wall_2()、wall_3() 和 wall_4() 方法中，您仅使用一个参数调用 price_all_walls() （墙的价格）。这将引发错误 "the function definition does not exist"。

当你定义一个函数时，一个函数原型与它相关联（尽管这个术语在 C 和 C++ 编程语言中最常用），其中包括方法的名称和类型签名（参数类型 -> 不适用）在 python、return 类型等）。当您调用方法 price_all_walls() 时，应该使用四个参数调用它，因此您的代码可以修改如下：

def wall_1():
   height = int(input("Enter the height in meters of wall 1 :"))
   width = int(input("Enter the width in meters of wall 1:"))
   wall_1_price = height * width
   wall_2(wall_1_price)

def wall_2(wall_1_price):
   height = int(input("Enter the height in meters of wall 2:"))
   width = int(input("Enter the width in meters of wall 2:"))
   wall_2_price = height * width
   wall_3(wall_1_price, wall_2_price)

def wall_3(wall_1_price, wall_2_price)
   height = int(input("Enter the height in meters of wall 3:"))
   width = int(input("Enter the width in meters of wall 3:"))
   wall_3_price = height * width
   wall_4(wall_1_price, wall_2_price, wall_3_price)

def wall_4(wall_1_price, wall_2_price, wall_3_price):
   height = int(input("Enter the height in meters of wall 4:"))
   width = int(input("Enter the width in meters of wall 4:"))
   wall_4_price = height * width
   price_all_walls(wall_1_price, wall_2_price, wall_3_price, wall_4_price)

def price_all_walls(wall_1_price, wall_2_price, wall_3_price, wall_4_price):
   print("The total price so far is : " + str(wall_1_price + wall_2_price + wall_3_price + wall_4_price))

if __name__=="__main__":
   wall_1()

虽然这是一种非常低效的方法（没有优秀的程序员会建议这样做）。这个例子很好地解释了手头的问题。

如果您想编写此问题的代码，我建议您使用全局变量或按照以下代码所示的方式进行：

def wall_1():
   height = int(input("Enter the height of wall 1 :"))
   width = int(input("Enter the width of wall 1 :"))
   wall_1_price = height * width
   return wall_1_price

def wall_2():
   height = int(input("Enter the height of wall 2:"))
   width = int(input("Enter the width of wall 2:"))
   wall_2_price = height * width
   return wall_1_price

def wall_3():
   height = int(input("Enter the height of wall 3:"))
   width = int(input("Enter the width of wall 3:"))
   wall_3_price = height * width
   return wall_3_price

def wall_4():
   height = int(input("Enter the height of wall 4:"))
   width = int(input("Enter the width of wall 4:"))
   wall_4_price = height * width
   return wall_4_price

def price_all_walls(wall_1_price, wall_2_price, wall_3_price, wall_4_price):
   return wall_1_price + wall_2_price + wall_3_price + wall_4_price

if __name__=="__main__":
   wall_1_price = wall_1()
   wall_2_price = wall_2()
   wall_3_price = wall_3()
   wall_4_price = wall_4()
   print("The total price of the walls is : " + str(price_all_walls(wall_1_price, wall_2_price, wall_3_price, wall_4_price)))

尽管有人会建议执行此操作的最佳方法如下。声明一个函数 wall_n(int, int)，它将高度和宽度作为参数，returns 是墙的价格。这导致了模块化代码，也提供了可重用性。

def wall_n(height, width):
   wall_n_price = height * width 
   return wall_n_price

def price_all_walls(prices):
   total_price = 0
   for price in prices:
      total_price += price
   return total_price

if __name__=="__main__":
   number_walls = int(input("Enter the number of walls to build : "))
   wall_prices = []
   for i in range(number_walls):
      height = int(input("Enter the height of wall " + str(i) + " : "))
      width = int(input("Enter the width of wall " + str(i) + " : "))
      wall_prices.append(wall_n(height, width))
   print("The total price is : " + str(price_all_walls(wall_prices)))

我没有演示全局变量的使用。你可以阅读它 here

我希望这能回答你的问题。

Python 如何在另一个子例程中使用来自子例程的输入

Python how to use inputs from sub routines in another sub routine

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