Question

Could someone please explain why these two pieces of Java codes are behaving differently? First one correctly counts number of bits but the second one just displays 1 or 0 for non-zero numbers. I don’t understand whats happening.

    public static void printNumUnitBits(int n){
    int num=0;
    for(int i=0;i<32;i++){
        int x=n&1;
        num=num+x;
        n=n>>>1;
        }
     System.out.println("Number of one bits:"+num);
    }

    public static void printNumUnitBits(int n){
    int num=0;
    for(int i=0;i<32;i++){
        num=num+n&1;
        n=n>>>1;
        }
     System.out.println("Number of one bits:"+num);
    }

Answer 1

In Java, + has higher precedence than &. Your expression num+n&1 will add num and n and then take the lowest bit.

To fix this, try making the statement in the second example num=num+(n&1);.