如何循環 python 列表輸入驗證？

Question

newcompany = input("Enter Company Name: ")
for stock in portfolioStock:
    if newcompany.lower() == stock[0].lower():
        newcompany = input("Company already exist in the Portfolio\nPlease enter another Company Name: ")
        break
    else:
        newcompany = newcompany.capitalize()
        continue

上面的代碼只檢查一次輸入驗證，然后再繼續我的下一個代碼塊，我如何讓它連續驗證輸入。 例如輸入，我輸入了apple，但是我的列表中有apple，所以它再次提示，但是當我再次輸入apple時，它只是移動到下一行代碼。

Enter Company Name: apple
Company already exist in the Portfolio
Please enter another Company Name: apple
Enter market capitalisation of company: Mega, Large or Mid: 

這就是它的樣子

接下來是while循環

newcompany = input("Enter Company Name: ")
while True:
    for stock in portfolioStock:
        if newcompany.lower() == stock[0].lower():
            newcompany = input("Company already exist in the Portfolio\nPlease enter another Company Name: ")
            break
        else:
            newcompany = newcompany.capitalize()
            continue

這就是我的代碼在while循環中的樣子 這些是結果

Enter Company Name: apple
Company already exist in the Portfolio
Please enter another Company Name: apple
Company already exist in the Portfolio
Please enter another Company Name: samsung

它在三星下方留下一個空格，並且不會繼續到下一行代碼

Answer 1

我不完全清楚你在找什么。 假設portfolioStock是一個list列表，這可能對您有用。

newcompany = input("Enter Company Name: ")
for stock in portfolioStock:
  #Convert all elements in list to lowercase
  stock = [x.lower() for x in stock]
  #This loop wil continue as long as the input is equal to any value in stock
  while newcompany.lower() in stock:
    newcompany = input("Company already exist in the Portfolio\nPlease enter another Company Name: ")
  newcompany = newcompany.capitalize()

Answer 2

使用while循環檢查公司是否已經存在，如果存在，它將不斷提示您輸入新名稱。 當有新名稱時，它將被添加到列表中

portfolioStock = ["Apple"]
company = input("Enter Company Name: ")
while company.capitalize() in portfolioStock: # e.g. 'Apple' is already in there
    company = input("Company already exist in the Portfolio\nPlease enter another Company Name: ")

portfolioStock.append(company.capitalize())

Answer 3

謝謝米切爾·奧利斯拉格斯！！

newcompany = input("Enter Company Name: ")
for stock in portfolioStock:
    while newcompany.lower() == stock[0].lower():
        newcompany = input("Company already exist in the Portfolio\nPlease enter another Company Name: ")
    newcompany = newcompany.capitalize()

因為我的投資組合股票是一個包含 str 和 int 的 2D 列表，所以我不得不稍微編輯 Mitchell 的代碼，但它可以工作！！！ 太感謝了！！