循环时无法逃脱

Question

我是一位在Python 3.5中为我的Computer Concepts III类编写的开始程序员。本周我们正在尝试使用try/except块和布尔标志来修改我们上周制作的程序。除了一件事我几乎完成了我的每周任务。我无法弄清楚为什么我在一个while循环中卡住了。这是有问题的循环：

while not valid_data: 
    cont = input("Would you like to order another? (y/n) ") 
    if cont.lower not in yorn: 
     valid_data = False 
    else: 
     valid_data = True 

yorn是["y", "n"]

这里是上下文整个程序：

# Program  Lesson 6 Order 
# Programmer Wiley J 
# Date   2016.02.13 
# Purpose  The purpose of this program is to take an order for cookies. 


# Import Class/Format Currency 
import locale 
locale.setlocale(locale.LC_ALL, '') 

# Define Variables 
boxes = 0 
cost = 3.50 
qty = 0 
items = 0 
yorn = ["y", "n"] 

# Banner 
print("Welcome to The Cookie Portal") 

# Input 
valid_data = False 

while not valid_data: 
    name = input("Please enter your name: ") 
    if len(name) > 20: 
     print() 
     print("Not a valid name") 
     valid_data = False 
    elif len(name) == 0: 
     print("You need to enter a name") 
     valid_data = False 
    else: 
     print("Hello", name) 
     valid_data = True 

cont = input("Would you like to place an order? (y/n) ") 

# Process 
while cont.lower() not in yorn: 
    cont = input("Would you like to place an order? (y/n) ") 

while cont.lower() == "y": 

    valid_data = False 

    while not valid_data: 
     print("Please choose a flavor:") 
     print("1. Savannahs") 
     print("2. Thin Mints") 
     print("3. Tagalongs") 
     try: 
      flavor = int(input("> ")) 
      if flavor in range (1, 4): 
       items += 1 
       valid_data = True 
      else: 
       valid_data = False 
     except Exception as detail: 
      print("Error", detail) 

    valid_data = False 

    while not valid_data: 
     try: 
      boxes = int(input("How many boxes? (1-10) ")) 
      if boxes not in range (1, 11): 
       print("Please choose a number between 1 and 10") 
       valid_data = False 
      else: 
       qty += boxes 
       valid_data = True 
     except Exception as detail: 
      print("Error", detail) 
      print() 
      print("Please enter a number") 

    valid_data = False 

    while not valid_data: 
     cont = input("Would you like to order another? (y/n) ") 
     if cont.lower not in yorn: 
      valid_data = False 
     else: 
      valid_data = True 



# Output 
if cont.lower() == "n": 
    cost *= qty  
    print() 
    print("Order for", name) 
    print("-------------------") 
    print("Total Items = {}".format(items)) 
    print("Total Boxes = {}".format(qty)) 
    print("Total Cost = {}".format(locale.currency(cost))) 
    print() 
    print("Thank you for your order.") 

是否有与此代码的其他问题我也不会感到惊讶但他们很可能按照任务的要求进行设计。欢迎任何额外的反馈。

Answer 1

看来你缺少功能paranthesis中的“较低”结尾，像这样：

if cont.lower() not in yorn: 

Answer 2

你的问题是在这里：

if cont.lower not in yorn: 

下是一种方法，它应该是：

if cont.lower() not in yorn: 

Answer 3

在你的代码中，你在做cont.lower not in yorn。 [some string].lower是一个函数，而不是一个属性，所以你必须在它后面加括号来调用它。

cont = input("Would you like to order another? (y/n) ") 
if cont.lower() not in yorn: 
    valid_data = False 
else: 
    valid_data = True 

Answer 4

你.lower后缺少一个括号：

if cont.lower() not in yorn: