How to request optional additional input in Python?

Question

for example if I want a program two add the input numbers but I don't know if user will input 2,3 or 4 numbers, how can I add optional but not required input?

Answer 1

Hmm... Then I think a while loop will work. Keep appending inputs to a list until the user inputs “end” or some other keyword. Then check the length of your list and use it to guide the rest of the code.

Answer 2

There are a few ways. I think the best one is to get the input, which is by default a string, and split it number by number.
Lets say the user inputs the following:

3 7 35

You could turn that in a list [“3”, “7”, “35”] by using:

mylist = input().split(“ “)

Then you can turn each element of the list into an int by using list comprehension:

mynumbers = [int(x) for x in mylist]

Which will give you a list [3, 7, 35].
That would work for any number of numbers in the input.

If you want to add them all, do:

mysum = 0
for n in mynumbers:
mysum += n
print(mysum)

Answer 3

That wasn't really my question...my problem is, I need to find a way to make the program run one way if user inputs 3 things and another way if they input 4 separate inputs

Answer 4

Thanks, that is a great idea!😀