what do you mean by (a&1) in c++?

Question

In some c++ code I have seen that someone using a statement like

while(a) { //here a is an integer variable
    if(a&1) {
        //some expression
    }
}

now my question is what is the meaning of a&1 ?

Answer 1

It checks if a number is odd using bitwise operations. The last bit in a binary number is the ones place (or the 2^0 place). All odd numbers are going to have this bit turned on; it is what makes them odd. Therefore, by checking if a number has its last bit on (which is what & 1 does), you are actually checking whether or not it is odd. Since it uses bitwise operations, it is considerably faster than using modulo 2 for this purpose.

Answer 2

Here, & is the bitwise AND operator.

a&1 (or, rather a & 1) checks the LSB of a to be SET or not.