将&&（逻辑和）运算符转换为|| （逻辑或）运算符

Question

bool a, b;

A)
if (a && b)
    return true;
else
    return false;

B)
if (!a || !b)
    return false;
else
    return true;

I am little bit confused. Are A & B equivalent??

Answer 1

Yes, they are equivalent, because of De Morgan's laws:

!(a && b) == !a || !b

hence

 (a && b) == !(!a || !b)

However, at any decent company, one would get fired quickly if one wrote code like this.

if (<condition>)
    return true;
else
    return false;

is redundant, and it's more readable to write

return <condition>;

instead. (maybe return <condition> != 0 if you need to always ensure a 0 or 1 result, but this is already the case in your code, since && and || are guaranteed to yield 0 or 1.)

Answer 2

Yes they are. The first one is simply checking if both of them are true, and the second one checks if either of them are false. Both of them still return true if both are true, and false if not.