How does the function return a true/false value?

Question

Got the correct code for the challenge but I don't understand how the return line in the function evaluates to a boolean value. Why doesn't it evaluate to an actual integer rather than a boolean value? Which lesson in the course went over this concept?
```
import random
start = 5
def even_odd(num):        
    return not num % 2
while start:
    num = random.randint(1, 99)
    if even_odd(num):
        print("{} is even.".format(num))
    else:
        print("{} is odd.".format(num))
    start -= 1
```

Chris Freeman · Accepted Answer

Good question!
What I don't get is how num % 2 leads to True/False.
Specifically, num % 2 doesn’t directly lead to a True or False. Since it is modulo 2, it will always return either a 0 or a 1. It is the not preceding the expression that interprets the 0 or 1 in a truthy fashion (or context). Where, not 0 Becomes True and not 1 becomes False. 
Post back if you need more help. Good luck!!!

Alex Koumparos · Answer

Hi Chailette,
Python has the concept of 'truthy' and 'falsey'. For every built-in data type some values behave as though they are True (thus 'truthy') and others behave like they are False (falsey).
it's discussed in this (https://teamtreehouse.com/library/you-cant-handle-the-truth) video and you should also check out this helpful Stack Overflow question (https://stackoverflow.com/questions/39983695/what-is-truthy-and-falsy-in-python-how-is-it-different-from-true-and-false) (which includes a list of which values are truthy and falsey for each data type).
Simply put, you can substitute a truthy value when you are checking for a boolean True and get the same result. For example:
Python
if 5:
    print("5 is truthy!")

The only practical distinction between a truthy value and a real True is that they are not strictly equal:
Python
if 5 == True:
    print("it's True!")
else:
   print("it's not True!")

Will print "it's not True!".
Hope that makes sense
Cheers
Alex

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chailatte

chailatte

How does the function return a true/false value?

2 Answers

Chris Freeman

Chris Freeman

chailatte

chailatte

Alex Koumparos

Alex Koumparos

chailatte

chailatte