这是我的代码,我不知道这个错误意味着什么。任何人请告诉我哪里做错了,什么应该是正确的代码。非常感谢帮助
代码:
cart = ['S/n'," "*10, 'Items', " " * 15, "Quantity", " " * 8, "Unit Price", " " * 6, "Price"]
total_pricee = 0
pricee = 0
count=1
cart_number=[count]
def invalid_input(Quantity):
while Quantity >= '5' or Quantity < '0':
Quantitiy = input("Please key in a valid quantity(Between 1 to 4):")
if Quantity <= '5' and Quantity > '0':
return Quantity
break
break
while not Quantity.isdigit():
Quantity = input('Invalid input.Please enter a valid input:')
while Quantity.isdecimal() == False:
break
def add_to_cart(name, Quantity, price):
global total_pricee, pricee,count
cart.append('\n')
cart.append('{:<10s}'.format(str(count)+'.'))
cart.append('{:^10s}'.format(name))
cart.append('{:^30s}'.format(Quantity))
cart.append('{:^10s}'.format('$' + '{:.2f}'.format(float(price))))
pricee = '{:.2f}'.format(float(Quantity) * price)
cart.append('{:^23s}'.format('$' + str(pricee)))
total_pricee += float(pricee)
count = count +1
while True:
print('[1] Water')
print('[2] rice')
print('[3] ice')
print('[0] View Cart')
opt = input("Select option:")
if opt > '3' or opt < '0':
print("Select valid option!")
if opt == '3':
qunt = input("How many would you like?")
qunt=invalid_input(qunt)
nam3 = "Ice"
add_to_cart(nam3, qunt, 2)
if opt == '1':
qunt2 = input("How many would you like?")
quan2=invalid_input(qunt2)
nam2 = "Water"
add_to_cart(nam2, qunt2, 3)
if opt == '2':
qunt1 = input("How many would you like?")
qunt1=invalid_input(qunt1)
nam1 = "Rice"
add_to_cart(nam1, qunt1, 5)
if opt == "0":
print(*cart)
print("Total price until now:", "$" + '{:.2f}'.format(total_pricee))
print('Would you like to check out?')
print('[1] Yes')
print('[2] No')
checkout=input("Please select an option:")
if checkout=='1':
print('You have bought',count,'items')
print("Please pay""$" + '{:.2f}'.format(total_pricee))
print('Thank you for shopping with us!')
exit()
我得到这个错误:
TypeError: unsupported format string passed to NoneType.__format__
我只是说学习python,我不知道这个错误是什么意思。任何人请告诉我哪里我做错了,什么应该是正确的代码。非常感谢您的帮助,非常感谢
查看使用.format方法的代码行。至少在其中一个中,您有一个空值,并且您正在尝试对其使用.format方法-这是您无法做到的。 因此出现错误:NoneType.format
在每次操作之前打印所有变量,或者添加一些逻辑来检查空值,例如
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