Question

我的代码出现问题。循环仅运行一次用户输入的数字。谢谢你的帮助。

#create an empty list and ask the user how many items they want to add  
# take the items the user entered and add it to the empty list.
print("enter the number of items")
x = int(input(">")) #take number of user input with the type int
print("thanks")
print("enter your food items")
fitems = [] # empty list
for i in range(x): #range to limit the number of iteration the user entered.
    items = input (">") #taking the items from the user 
    empty = ""
    if (items == empty):# checking if the user added nothing
        print("no items added")
    break
else:
    fitems.append(items) #add the list of items the user entered to the 
empty list
    print("hello here is your food items: \n",fitems) #output user items

Answer 1

您的代码中缺少一些缩进，还有其他一些错误。这是（我认为）正确的代码：

print("enter the number of items")
x = int(input(">"))
print("thanks")
print("enter your food items")
fitems = []
for i in range(x):
    items = input(">").strip() # there was a space before first bracket in your code, it's possible to have it there, but this is better
    # edit: added .strip(), it removes extra whitespace from beginning and end
    if items == "": # no need to create empty string variable, compare simply with empty string,
    # edit: you can also use 'if not items:', because empty string evaluates to false
        print("no items added")
        break # break only if nothing added, so indent break to be only executed if empty
    fitems.append(items) # you don't have to have else here, break ends the loop, so this is not executed then
print("hello here are your food items: \n",fitems) # remove 1 indent, print only after loop ended

Answer 2

这样可行，因为你没有缩进＆＃34; break＆＃34;在for循环中

#create an empty list and ask the user how many items they want to add  
 # take the items the user entered and add it to the empty list.
 print("enter the number of items")
 x = int(input(">")) #take number of user input with the type int
 print("thanks")
 print("enter your food items")
 fitems = [] # empty list
 for i in range(x): #range to limit the number of iteration the user entered.
    items = input (">") #taking the items from the user 
    empty = ""
    if (items == empty):# checking if the user added nothing
       print("no items added")
       break #your error corrected
    else:
       fitems.append(items) #add the list of items the user entered to the 
  empty list
    print("hello here is your food items: \n",fitems) #output user items

Answer 3

我认为代码中唯一的问题是标识，所以你应该这样改变：

print("enter the number of items")
x = int(input(">")) #take number of user input with the type int
print("thanks")
print("enter your food items")
fitems = [] # empty list
for i in range(x): #range to limit the number of iteration the user ente red.
    items = input (">") #taking the items from the user 
    empty = ""
    if (items == empty):# checking if the user added nothing
        print("no items added")
        break
    else:
        fitems.append(items) #add the list of items the user entered to the 

print("hello here is your food items: \n",fitems)

Answer 4

首先，break语句和else语句没有正确使用。此外，当你使用.append（）时，你应该添加一个i + = 1来循环x，用户输入。

这将有效：

for i in range(x): #range to limit the number of iteration the user entered.
    items = input (">") #taking the items from the user
    empty = ""
    if (items == empty):# checking if the user added nothing
        print("no items added")
        break
    else:
        fitems.append(items) #add the list of items the user entered to the
        i += 1

Answer 5

如果没有输入任何内容，将导致无打印：

print("enter the number of items")
x = int(input(">")) #take number of user input with the type int
print("thanks")
print("enter your food items")
fitems = [] # empty list
for i in range(x): #range to limit the number of iteration the user entered.
    items = input (">") #taking the items from the user 
    empty = ""
    if (items == empty):# checking if the user added nothing
        print("no items added")
        break
    else:
        fitems.append(items) #add the list of items the user entered to the\
                                                                empty list
if len(fitems)==0:
    pass
else:
    print("hello here is your food items: \n",fitems)

Answer 6

我冒昧地做出一些改变。试试这个：

# create an empty list and ask the user how many items they want to add  
# take the items the user entered and add it to the empty list.

fitems = []

# Define valid input for amount of items
valid = [str(i) for i in range(1,10)] # ["1","2"...."9"]

# If item is not in the list of valid, continue asking
while True:
    print("enter the number of items [1-9]")
    x = input(">")
    if x in valid:
        break

# Convert to int
itemamount = int(x)
print("thanks\nenter your food items")

# Now ask for inputs using while > 0 and remove itemamount in each loop
while itemamount > 0:
    while True:
        item = input (">")
        if item:
            break
        print("Blank input")
    fitems.append(item)
    itemamount-=1

print("hello here is your food items: ")
for ind,i in enumerate(fitems,1):
    print("{}. {}".format(ind,i))

循环只运行一次

6 个答案: