Question

大家好，这是我正在为学校工作编写的示例代码。

class Item:
    
    list = []
    
    def __init__ (self, name, num):
        Item.list.append(self)
        self.name = name
        self.num = num
        
bread = Item("Bread", 20)
rice = Item("Rice", 30)
fruits = Item("Fruits", 40)
vegetables = Item("Vegetables", 25)
meat = Item("Meat", 35)

for i in Item.list:
    print(f"{i.name}, {i.num}")

def withdraw():
    b = int(input(print("\nHow many bread would you take? "))) 
    r = int(input(print("\nHow many rice would you take? ")))  
    f = int(input(print("\nHow many fruits would you take? "))) 
    v = int(input(print("\nHow many vegetables would you take? ")))
    m = int(input(print("\nHow many meat would you take? ")))
   
    bread.num = bread.num - b
    rice.num = rice.num - r
    fruits.num = fruits.num - f
    vegetables.num = vegetables.num - v
    meat.num = meat.num - m
withdraw()

for i in Item.list:
    print(f"{i.name} : {i.num}")

每次打印的输出都是这样

How many bread would you take
None

为什么打印 None？我怎么能阻止它。谢谢。

Answer 1

尝试改变这些：

b = int(input(print("\nHow many bread would you take? "))) 
r = int(input(print("\nHow many rice would you take? ")))  
f = int(input(print("\nHow many fruits would you take? "))) 
v = int(input(print("\nHow many vegetables would you take? ")))
m = int(input(print("\nHow many meat would you take? ")))

到：

b = int(input("\nHow many bread would you take? ")) 
r = int(input("\nHow many rice would you take? "))  
f = int(input("\nHow many fruits would you take? ")) 
v = int(input("\nHow many vegetables would you take? "))
m = int(input("\nHow many meat would you take? "))

为什么每次我要求用户输入时都输出“none”？

1 个答案: