Explain please how the next code works

Question

I didn't get how "a" or "b" works
https://code.sololearn.com/coLCIglQOFcf/?ref=app

Answer 1

Hi Anton

You have to laborate with ‘and’ and ‘or’ a bit to understand it. Try using parantheses around:

(a and b) or c

respective:

a and (b or c)

Set a, b and c to True or False and test different cases.

You can even try bool("a") will give a True value, while bool("") gives a False value.

So in your case you tests it will works like this:

>>> x = 5
>>> print(("a" and x < 7) or "b")
True

>>> x = 5
>>> print((x < 7 and "a") or "b")
a

>>> x = 10
>>> print((x < 7 and "a") or "b")
b

Answer 2

Thanks for such a detailed answer

Answer 3

Every value in Python are either falsy or truthy. For example 0, set(), (), {}, [], 0.0 is falsy. 1, 5, -2.5, (1, 3), [1, 2, 3] etc is truthy.
(Test them whit bool().)

When you use ’and’ or ’or, the first value that satisfy the expression vill be returned. If it is a value that return False or True that will be delivered. But if it is an other value, for example a number (how also can be false or true, it return its value. So 4 and True vill retern True, True and 4 vill return 4. 4 or True vill return 4 (because 4 is a truthy value and ’or’ gives that if on value is true, the hole expression is true (it reads from left to right and stop reading when satisfied)). Try!

Answer 4

Very interesting question and answer! Thanks Anton and Per Bratthammar for the insight!

Answer 5

Now it is clearer for me )

Answer 6

Wait a second, I understand the boolean logic
But in this code we compare the bool value to a string. How so?
We get:
7>5 and "a" or "b"
True and string or string