Meaning of bitwise and(&) of a positive and negative number?

Question

Can anyone help what n&-n means?? And what is the significance of it.

Answer 1

It's just a bitwise-and of the number. Negative numbers are represented as two's complement.

So for instance, bitwise and of 7&(-7) is x00000111 & x11111001 = x00000001 = 1