[Introduction to programming in Java 笔记] 1.3.7 Converting to binary 十进制到二进制的转换

public class Binary
{
    public static void main(String[] args)
    {   // Print binary representation of N.
        int N = Integer.parseInt(args[0]);
        int v = 1;
        while(v <= N/2)
            v = 2*v;
        // Now v is the largest power of 2 <= N.
        int n = N; // current excess
        while (v > 0)
        { //Cast out the power of 2 in decreasing order.
            if (n < v) { System.out.print(0);    }
            else       { System.out.print(1); n-=v;}
            v = v/2;
        }
        System.out.println();
    }
}

打印10进制数字（decimal number）的二进制表示。将数字拆成2的幂次的和的形式。例如 19 = 16 + 2 + 1. 所以 19 的二进制表示为 10011.