Boolean operators returning values is common, especially in dynamically typed languages. The code is valid in JavaScript, for example, and in Python (except it uses "or" instead of "||").

In python, it should probably be corrected with // or 1.0 to make it either an integer division or a float division.

Ah, that's true. Good point.

This is valid C and C++.

It is, but it will always give you a divisor of 1 (because "true" is 1 -- I also thought it would work until I tested it):

    % cat >division.c <<EOF
    #include <stdio.h>
    
    int main(void)
    {
            printf("1/0 = %d\n", 1 / (0 || 1));
            printf("1/2 = %d\n", 1 / (2 || 1));
    
            printf("1.0/0 = %f\n", 1.0 / (0 || 1));
            printf("1.0/2 = %f\n", 1.0 / (2 || 1));
    }
    % gcc -Wall -o divison divison.c
    % ./divison
    1/0 = 1
    1/2 = 1
    1.0/0 = 1.000000
    1.0/2 = 1.000000

In Python this is not the case:

    % python3
    >>> 1 / (0 or 1)
    1
    >>> 1. / (0 or 1)
    1.0
    >>> 1 / (0 or 1)
    1
    >>> 1. / (2 or 1)
    0.5
    % python3
    >>> 1 / (0 or 1)
    1.0
    >>> 1 / (2 or 1)
    0.5

Some trivia: GNU extensions to C/C++ include a "?:" operator that does what you'd want in this case, e.g.

    x / (divisor ?: 1)

It shouldn't be valid in C++. booleans cannot participate in arithmetic operations. You will get a warning from the compiler if you are lucky.

C doesn't have booleans and treat them as integers 0 or 1, it can do the math and will always return 1.

That's not true. C++ does define an implicit conversion from bool to int:

https://en.cppreference.com/w/cpp/language/implicit_conversi... (under "Integral promotion")

And C has a boolean type as of C99.

What do you expect for that C code?

In the context of this discussion, the idea was that it would act the same way as Python. But it obviously doesn't.