Python 3 sum 2 integers with input. ValueError: invalid literal for int() with base 10: '1 1'

Question

I am trying to add 2 integers in Python3 using input.

def sum(x,y):
    return x+y
a = int(input("Enter first number"))
b = int(input("Enter second number"))
print("The sum of a and b is", sum(a,b))

and get the following error

Traceback (most recent call last):
File "Main.py", line 7, in <module>
a = int(input("Enter first number"))
ValueError: invalid literal for int() with base 10: '1 1'

Another concern is this works normally in my Jupyter notebook, but for another online practice center it shows this error.

What is the input you are giving? It looks like you are trying to convert `'1 1'` to an `int`. — iz_, Jan 09 '19 at 05:13
the first step in debugging should be to split `int(input(..))` into two statements so that you can examine the result of `input(..)` to see if it's what you are assuming it is. — Bryan Oakley, Jan 09 '19 at 05:14
You are not giving the right input mate. Giving input as 1 1 as Tomothy said, would obviously give you this error. Because Python is converting this input of 1 1 into integer and it can convert '11' to int but not '1 1'. Of course it's supposed to give this error. — Amit Amola, Jan 09 '19 at 05:16
Possible duplicate of [ValueError: invalid literal for int () with base 10](https://stackoverflow.com/questions/13861594/valueerror-invalid-literal-for-int-with-base-10) — Amit Amola, Jan 09 '19 at 05:17
@Tomothy32 The practice center is providing that input, it looks like two space separated integers? Is that a problem with this code? — Shaner, Jan 09 '19 at 05:20
@AmitAmola The practice center inputs into my code, I don't think this is a duplicate of the other question as it is not a float number is it? — Shaner, Jan 09 '19 at 05:22
If you see below that float answer, the answerer does mention about spaces as well. That's why I marked it as a duplicate. Now see, if the input is going to be like that only, then you can use .replace(" ","") and this would work perfectly fine I believe. — Amit Amola, Jan 09 '19 at 05:40

score 0 · Answer 1 · answered Jan 09 '19 at 05:30

Your code is working, but not for the specific input the practice center is giving. Make this modification:

nums = [int(x) for x in input("Enter numbers: ").split()]
print("The sum of a and b is", sum(nums))

By the way, sum is a built-in function, so you don't have to write it yourself. The only line that really changed is this:

nums = [int(x) for x in input("Enter numbers: ").split()]

nums will be a list of numbers, as the name implies. The next part is the list comprehension. input("Enter numbers: ").split() will take the input and split it on any whitespace. For instance, 'hello world' will be turned into a list with ['hello', 'world']. In this case, '1 1' will be turned into a list with ['1', '1']. Then, with the list comprehension, you are turning each element into an integer (['1', '1'] -> [1, 1]). Then, you pass this list into sum. Also, this does the same thing as the list comprehension:

nums = list(map(int, input("Enter numbers: ").split()))

It doesn't matter which one you choose. If you wanted to get real fancy, you can do the whole thing in one line:

print("The sum of a and b is", sum(map(int, input("Enter numbers: ").split())))

score 0 · Answer 2 · answered Jan 09 '19 at 05:43

Given that your input are coming with spaces itself, you can use replace command and replace those spaces.

def sum(x,y):
    return x+y

a = int(input("Enter first number: ").replace(" ",""))
b = int(input("Enter second number: ").replace(" ",""))
print("The sum of a and b is: ", sum(a,b))

For your specific case, this should work. What I am doing here is that I am converting the input like '8 3 525 5', to '835255', which itself will be easily converted to int later on and will work perfectly.

Removing the duplicate as well mate.

score 0 · Answer 3 · answered Jan 09 '19 at 05:52

If you want to input all values in the same line as 1 1, then you should use split():

def sum(x,y):
    return x+y

a, b = map(int, input("Enter numbers ").strip().split())
print("The sum of a and b is", sum(a,b))

Output:

C:\Users\Desktop>py xxx.py
Enter numbers 1 1
The sum of a and b is 2

If separately values need to be inputted:

def sum(x,y):
    return x+y

a = int(input("Enter first number ").strip())
b = int(input("Enter second number ").strip())

print("The sum of a and b is", sum(a,b))

Output:

C:\Users\Desktop>py xxx.py
Enter numbers 1 1
The sum of a and b is 2

Python 3 sum 2 integers with input. ValueError: invalid literal for int() with base 10: '1 1'

3 Answers3