Question

我正在浏览Python的初学者指南，而我目前正在处理列表。现在我已经创建了这个示例代码，但我似乎无法将用户输入动态添加到我创建的列表中。如果您从列表中输入项目，则会收到成功消息，但如果该项目不在列表中，我会尝试将其附加到当前列表，然后我返回一条错误消息，表明它不是在库存中。最后一行只是打印出列表，希望新增加。我已经尝试过append方法，甚至尝试扩展到另一个列表。有人可以发现我出错的地方吗？

topping_list_one = ['pepperoni', 'sausage', 'cheese', 'peppers']
error_message = "Sorry we don't have "
success_message = "Great, we have "

first_topping = raw_input ('Please give me a topping: ')
if ( first_topping in topping_list_one ) :
    print '{}!'.format(success_message + first_topping) 
elif ( first_topping in topping_list_one ): 
    topping_list_one.append('first_topping')
else : 
    print '{}'.format(error_message + first_topping)
print 'Heres a list of the items now in our inventory: {}'.format(topping_list_one)

Answer 1

我想你的意思是说

elif ( first_topping not in topping_list_one ): 
    topping_list_one.append(first_topping)

即。＆＃34;不在＆＃34;而不是＆＃34;在＆＃34;并从＆＃39; first_topping＆＃39;

中删除引号

Answer 2

您的代码不是很一致，也有一些错误。你应该只有两个procedure TForm1.Timer3Timer(Sender: TObject);//200ms delphi timer var OriginalShots, CurrentShots: array [0..MAX_PATH] of AnsiChar; begin timer2.Enabled := false; Win32Check(ReadProcessMemory(hProc, pointer(BaseEU + AddrShotsLeft), @CurrentShots, SizeOf(CurrentShots), Read)); CurrentShots := OriginalShots;//this will ofcourse set both variables to the same value everytime, how can i do this properly? if CurrentShots < OriginalShots then begin //do stuff here UpdateOrAdd(Memo1, 13, 'Shots Left: '+string(CurrentShots)); end; end;条件。如果顶部在列表中，则打印它，如果不是，则添加新的或仅显示错误消息。

当然，如果你创造一个不添加特殊字符的条件，那么你可以同时拥有这两个字符。

添加新的顶部：

if

错误讯息：

topping_list_one = ['pepperoni', 'sausage', 'cheese', 'peppers']
error_message = "Sorry we don't have "
success_message = "Great, we have "

first_topping = raw_input ('Please give me a topping: ')
if first_topping in topping_list_one :
    print '{}!'.format(success_message + first_topping) 
else :
    topping_list_one.append(first_topping)
print 'Heres a list of the items now in our inventory: {}'.format(topping_list_one)

这两种：

topping_list_one = ['pepperoni', 'sausage', 'cheese', 'peppers']
error_message = "Sorry we don't have "
success_message = "Great, we have "

first_topping = raw_input ('Please give me a topping: ')
if first_topping in topping_list_one :
    print '{}!'.format(success_message + first_topping) 
else : 
    print '{}'.format(error_message + first_topping)
print 'Heres a list of the items now in our inventory: {}'.format(topping_list_one)

PS：未经测试，纯粹是理论上的。

Answer 3

您的前两个条件语句完全相同，并且根据您对目标的描述，我认为您需要在else流程下附加用户输入，如下面的代码。

topping_list_one = ['pepperoni', 'sausage', 'cheese', 'peppers']
error_message = "Sorry we don't have "
success_message = "Great, we have "

first_topping = raw_input ('Please give me a topping: ')
if first_topping in topping_list_one:
    print '{}!'.format(success_message + first_topping)  
else: 
    print '{}'.format(error_message + first_topping)
    topping_list_one.append(first_topping)
print 'Heres a list of the items now in our inventory:{}'.format(topping_list_one)

BTW我指出了你的代码的两个问题

你需要用Python编写它，在其他语言中忘记if()，python在条件语句中不需要括号（尽管添加括号不会触发语法错误）。
追加变量first_topping而非字符串first_topping，我认为它是由粗心大意引起的： - ）

将输入附加到现有列表

3 个答案: