Python - cannot convert string containing only numbers to an int

Question

I have about a hundred numbers contained as strings in a list, and I need to add all of them together. To do this, I'm using the following code -

for item in listo:
    sumo += int(item)

I'm getting a ValueError that says:

ValueError: invalid literal for int() with base 10: ''

I don't know what causes this particular error, rather than just the error that says that the string couldn't be converted to an int. Does anyone know what the problem is, and how to fix it?

EDIT - I found the error! I used the .split() method, and I accidentally added one too many period, creating an empty string.

I would guess what's happening is you're reading the list from a file, and the last entry is an empty line. Can you post a complete example that demonstrates the problem? — Greg Hewgill
– Greg Hewgill, Commented Jun 21, 2017 at 23:13
It indeed is! I used the split() method, and accidentally split it one time too many. Thanks for your help! — Sam Carpenter
– Sam Carpenter, Commented Jun 21, 2017 at 23:14
Note that you can use the sum(..) builtin with a generator, making it more declarative and a one-liner. — willeM_ Van Onsem
– willeM_ Van Onsem, Commented Jun 21, 2017 at 23:18

john · Accepted Answer · 2017-06-21 23:20:36Z

1

Type casting as intcan only be used if the passed string is valid. For eg. int('5') is valid but int('apple') is not.

The error is kind of self explanatory. The the parameter supplied to convert it to an integer is invalid. IF it was particular string it would have displayed that. Blank quotes would generally mean its an empty string you are trying to convert. It s good you have found the error yourself. generally the description of the error is a good pointer to what is wrong.

Good luck

answered Jun 21, 2017 at 23:20

john

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Jayakumar M · Accepted Answer · 2017-06-21 23:31:31Z

0

new_list = filter(None, list)
lisSum = sum(map(int,new_list ))

hope this is what your expecting

answered Jun 21, 2017 at 23:31

Jayakumar M

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