return not num % 2

Question

Hi, I don't quite understand what this does, could anyone give me a further explanation in a simple way please

Dave Harker · Accepted Answer

Hi youssef moustahib (https://teamtreehouse.com/youssefmoustahib2),
It's just going to return a boolean value. As I understand it, in python 0 is false, anything other number is true.
the not switches the boolean value to it's opposite value (true becomes false, false becomes true).  
Some examples to help it make more sense:
4%2 equals 0 which as a boolean expression equates to false  
          ... so not 4%2 (or not false) would return true
5%3 equals 2 which as a boolean expression equates to true  
          ... so not 5%3 (or not true) would return false
In short ANY expression that equals 0 in this context will return true, as it is not false
I hope that clears it up for you. Happy coding, :dizzy:  
Dave.

Chris Freeman · Answer

There are three things going on in the statement:
Python 
return not num % 2

The parsing starts from left to right:
return something
not something
something % something
Once parsed, there are resolved in the reverse order:
num % 2 says find the result of num modulo 2. This is remainder after dividing num by 2. If num is even, the result will be zero. If num is odd, the result will be 1. 
the not says invert the logical value of an object. This takes the modulo result and reverses its "truthiness". A 1 (from an odd num) is truthy, so not 1 becomes False.  A 0 (from an even num) is not truthy, so not 0 becomes True.  
the return simply returns the not result. 
Therefore:
* if num is even, True is returned 
* if num is odd, False is returned 
Post back if you need more help. Good luck!!!

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Youssef Moustahib

Youssef Moustahib

return not num % 2

2 Answers

Dave Harker

Dave Harker

Chris Freeman

Chris Freeman