Python counting with str and int

Question

Everyone, hello!

I'm not able to count properly, and I'm at a loss. A second pair of eyes would really be helpful.

I'm getting a variable from my config file as:

import ConfigParser
config = ConfigParser.ConfigParser()
config.read("config.ini")
count1 = config.get('Counter','count1')
>>> print count1
5

However, when I want to simply substract - 1 from this variable, as so:

count1 = (count1 - 1)

I'm confronted with an error:

TypeError: unsupported operand type(s) for -: 'str' and 'int'

Any help would be really appreciated. Thanks!

You are obviously trying to do a substraction of a str and an int, as the error message tells you. Since 1 is an int, then count1 must be a str. You can print type(count1) before the line that gives you the error to make sure of that. Then, just convert it with int(). — Efferalgan
– Efferalgan, Commented Oct 20, 2016 at 7:08

Francisco · Accepted Answer · 2016-10-20 07:10:49Z

4

You can't do arithmetic with strings, you have to convert it first to an integer with the int function:

count1 = int(config.get('Counter', 'count1'))

You could also use the config.getint or config.getfloat methods.

If you need a float, you can use the float function instead.

answered Oct 20, 2016 at 7:03

Francisco

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Comments

AKS · Accepted Answer · 2016-10-20 07:07:22Z

3

>>> count1 = config.get('Counter','count1')

Above will simply return a string type. And, that's why you are getting the error because you can't subtract an int from a string type.

If you need int from config, you can use RawConfigParser.getint method:

>>> count1 = config.getint('Counter','count1')

answered Oct 20, 2016 at 7:07

AKS

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