Java BigInteger Calculate getSize(BigInteger number)

Description

Returns the number of bits in the two's-complement representation of the given number, including a sign bit only if number is less than zero.

License

Open Source License

Parameter

Parameter	Description
number	a number

Return

the number of bits in the two's-complement representation of the given number, including a sign bit

Declaration

public static int getSize(BigInteger number)

Method Source Code


//package com.java2s;
import java.math.BigInteger;

public class Main {
    /**//from  ww  w  . j  a  va2s  .  com
     * Returns the number of bits in the two's-complement representation of the
     * given number, including a sign bit <i>only</i> if <code>number</code> is
     * less than zero.
     * 
     * @param number
     *            a number
     * @return the number of bits in the two's-complement representation of the
     *         given number, <i>including</i> a sign bit
     */
    public static int getSize(BigInteger number) {
        int cmp = number.compareTo(BigInteger.ZERO);
        if (cmp == 0) {
            // 0 is represented as a uint(size=1)
            return 1;
        } else {
            int bitLength = number.bitLength();
            return (cmp > 0) ? bitLength : bitLength + 1;
        }
    }

    /**
     * Returns the number of bits in the two's-complement representation of the
     * given number, including a sign bit <i>only</i> if <code>number</code> is
     * less than zero.
     * 
     * @param number
     *            a number
     * @return the number of bits in the two's-complement representation of the
     *         given number, <i>including</i> a sign bit
     */
    public static int getSize(long number) {
        return getSize(BigInteger.valueOf(number));
    }
}