循环只运行一次

Question

我的代码有问题。循环仅运行一次用户输入的号码。谢谢您的帮助。

#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

我冒昧地做出一些改变。试试看：

# 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)) 

Answer 2

这工作，因为你没有缩进“破发”里面的for循环

#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

我想在你的代码的唯一问题是identation，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

您在代码中缺少一些缩进，还有一些其他错误。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 5

首先break语句和else语句不是正确的。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。

这将工作：

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 6

这将导致无打印如果输入什么：

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)