Converting input string of integers to list, then to ints in python?

Question

I want the user to input an integer (6 digits long, so 123456 rather than just 1), and then convert that input into a list, [1,2,3,4,5,6].

I tried this:

user_input = list(input("Please enter an 8 digit number")
numbers = [int(i) for i in user_input]

I want to be able to perform mathematical stuff with the numbers list, but I keep getting the error "int is not iterable". To be frank, I'm not entirely sure what I'm doing, or sure that the "numbers = [...] " is even necessary, or if it should just be numbers = user_input. Trying numbers = [i for i in user_input] gets the same error.

Also, I realise I could either run a loop to get each number from the user, or ask them to use commas in between each in order to use the .split(","), but I'd rather not as it seems messy to the user.

Edit: I've been switching things between versions, so sorry for any confusion. This was written in 2.7, though I intend to use Python 3.

Aren't you in python 2? If so use raw_input instead of input — Zeugma
– Zeugma, Commented Oct 9, 2016 at 16:05
Your problem is somewhere else, not in the code your have shown here. — Sнаđошƒаӽ
– Sнаđошƒаӽ, Commented Oct 9, 2016 at 16:06

Banach Tarski · Accepted Answer · 2016-10-09 16:10:20Z

1

In Python 2.7, input() returns an integer. To read input as a string use the function raw_input() instead. Alternatively, you can switch to Python 3 and where input() always returns a string.

Also your solution isn't very neat in case the user is providing numbers with more than 1 digits. For example the string "123" can be interpreted as [1, 2, 3], [12, 3] and so on.

A neat solution is to ask the user to provide the input separated by spaces as follows x_1, x_2, ... x_n

Then your code in Python 3.0 will look like

lst = [int(x) for x in input().split()]

And for Python 2.7

lst = [int(x) for x in raw_input().split()]

answered Oct 9, 2016 at 16:10

Banach Tarski

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zvone · Accepted Answer · 2016-10-09 17:46:57Z

Function input behaves quite differently in Python 2 and in Python 3.

This seems to be Python 2. In Python 2, input evaluates entered data as Python code. If only digits are entered, input will return one integer. Converting that to a list is not possible, hence the error.

input is unsafe and causes many problems, so it is best to avoid it. Use raw_input instead.

user_input = raw_input("Please enter an 8 digit number: ")

This will return a string, e.g. '12345678'.

This can be converted to a list. The list will iterate through the string character by character.

digits = list(user_input)   # e.g. ['1', '2', '3', '4', '5', '6', '7', '8']

But that is not even needed, you can directly do as you did:

numbers = [int(i) for i in user_input]   # e.g. [1, 2, 3, 4, 5, 6, 7, 8]

BTW, the Python 3 version of input is the same as Python 2 raw_input.

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