如果不是 integer 提示用戶如何處理列表中的用戶輸入

Question

我正在尋找處理用戶在列表中輸入的方式，如果用戶輸入字母（字符串）而不是數字（整數），它會提示用戶他輸入了無效值並提示用戶再次嘗試。 這里有一些代碼：

def get_list_from_user():   # Prompt the user for a list of number
    while True:
        user_list = input(f"Enter {difficulty} number separated by space: ")
        user_list = user_list.split()
        user_list = [int(i) for i in user_list]
        if not len(user_list) == difficulty:
            print(f"Please chose {difficulty} number separated by space: ")
        else:
            break

    saved_user_list = user_list
    return saved_user_list

Answer 1

您可以使用此代碼。

def get_list_from_user():   # Prompt the user for a list of number
    while True:
        user_list = input(f"Enter {difficulty} number separated by space: ")
        user_list = user_list.split()
        try:
            user_list = [int(i) for i in user_list ]
        except:
            print("entered an invalid value")
            continue
        if not len(user_list) == difficulty:
            print(f"Please chose {difficulty} number separated by space: "           
        else:
            break

    saved_user_list = user_list
    return saved_user_list

Answer 2

您可以使用 try, except 語句。 如果 int() 失敗，它將拋出我們處理的異常。

        try:
            user_list = [int(i) for i in user_list]
        except ValueError:
            print("Invalid value")

完整代碼：

def get_list_from_user():   # Prompt the user for a list of number
    while True:
        user_list = input(f"Enter {difficulty} number separated by space: ")
        user_list = user_list.split()
        try:
            user_list = [int(i) for i in user_list]
        except ValueError:
            print("Invalid value")
            continue
    
        if not len(user_list) == difficulty:
            print(f"Please chose {difficulty} number separated by space: ")
        else:
            break

    saved_user_list = user_list
    return saved_user_list

Answer 3

我建議使用異常處理程序（try/except）。 這是一種方法：

difficulty = 3

def get_list_from_user():   # Prompt the user for a list of number
    while True:
        user_list = input(f"Enter {difficulty} numbers separated by space: ").split()
        try:
            user_list = [int(i) for i in user_list]
            if len(user_list) != difficulty:
                raise ValueError
            return user_list
        except ValueError:
            print('Invalid input')

print(get_list_from_user())