java 大数 操作

a+b

import java.util.Arrays;import java.util.Scanner;/** * @Title: Big_Plue.java * @Package * @Description: TODO * @author nutc * @date 2013-8-19 下午10:02:50 * @version V1.0 */public class Big_Plue {public static void main(String args[]) {Scanner sc = new Scanner(System.in);while (sc.hasNextLine()) {String s = sc.nextLine();String[] now = s.split(" ");char[] a = now[0].toCharArray();char[] b = now[1].toCharArray();plus(a, b);}}//全部的--都写成++了。。。。！！！！！！！！！public static void plus(char[] a, char[] b) {if (a == null || b == null)return;int length =( a.length > b.length ? a.length : b.length )+ 1;  //这里括号不可缺少啊 白痴！char[] sum = new char[length];Arrays.fill(sum, '#');int ia = a.length - 1, ib = b.length - 1, is = sum.length - 1, add = 0;while (ia >= 0 && ib >= 0) {int now = (a[ia] - '0' + b[ib] - '0' + add) ;sum[is] = (char) (now % 10 + '0'); // cast？add = now / 10;ia--;ib--;is--;}while (ia >= 0) {int now = (a[ia] - '0' + add);sum[is] = (char) (now % 10 + '0'); // cast？add = now / 10;ia--;is--;}while (ib >= 0) {int now = (b[ib] - '0' + add) ;sum[is] = (char) (now % 10 + '0'); // cast？add = now / 10;ib--;is--;}if (add > 0) {sum[0] = '1';}int i = 0;if (sum[i] == '#')i++;while (i < sum.length){System.out.print(sum[i]);i++;}System.out.println();}}