how to handle user input in list if it is not an integer prompt back the user-CodePudding

i'm looking to handle the way a user input in a list if the user enter a letter(string) instead of a number(integer) it prompt back the user that he entered an invalid value and prompt back the user for another try. here some code :

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

CodePudding user response：

You can use this code.

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

CodePudding user response：

I recommend using an exception handler (try/except). Here's one way to do it:

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())

CodePudding user response：

You could use a try, except statement. If the int() fails, it will throw a exception which we handle.

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

Full code:

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