Programming Tricks/Questions/Trivia

[Zer0Degree]

kay bored ko, ako ning buhion balik

[Programming Language]
C/C++ (I think applicable sa tanan)

[Question]
Recently naay programming question na nisikat sa interwebs which is this:

If x is an (binary) integer, what does (x & -x) compute?

x & -x returns 1 if bot bits are 1. else 0.

for example:
x = 15;
y = 9;

z = x & y;

x = 1111
y = 1001
-------------
z = 1001

so x & y yields 9 of decimal 1001.

& is bitwise operator.

[Sarevok]

x & -x returns 1 if bot bits are 1. else 0.

for example:
x = 15;
y = 9;

z = x & y;

x = 1111
y = 1001
-------------
z = 1001

so x & y yields 9 of decimal 1001.

& is bitwise operator.

sakto imo definition sa bitwise AND operator, pero ang question kay what is x & -x (read x AND two's complement of x)

[Zer0Degree]

sakto imo definition sa bitwise AND operator, pero ang question kay what is x & -x (read x AND two's complement of x)

i dont get u. if you want to get the binary digit of negative integer, then get it and make an expression of & with a postive x : )

[Sarevok]

i dont get u. if you want to get the binary digit of negative integer, then get it and make an expression of & with a postive x : )

But you missed the main question which is, "What does x & -x compute?". What do you get when you do this operation?