两个大数之间的相关运算

 1 import java.util.Scanner;
 2
 3 /*
 4  进行大数相加，只能对两个正数进行相加
 5 */
 6
 7 public class BigNumber
 8 {
 9     public static void main(String[] args)
10     {
11         Scanner scan=new Scanner(System.in);
12         String a,b;
13         while (scan.hasNext())
14         {
15             BigNumber big=new BigNumber();
16
17             a=scan.nextLine();
18             b=scan.nextLine();
19
20             System.out.println(big.bigNumberAdd(a,b));
21         }
22     }
23
24     public String bigNumberAdd(String x,String y)
25     {
26         //String result=null;
27
28         char[] a=x.toCharArray();
29         char[] b=y.toCharArray();
30
31         int lenA=a.length;
32         int lenB=b.length;
33
34         int len=lenA>lenB?lenA:lenB;
35         int[] result=new int[len+1];
36
37         //字符串反转
38         char[] A=new char[lenA];
39         char[] B=new char[lenB];
40         for (int i=0;i<lenA;i++)
41         {
42             A[i]=a[lenA-i-1];
43         }
44
45         for (int j=0;j<lenB;j++)
46         {
47             B[j]=b[lenB-j-1];
48         }
49
50         //对应数字相加
51         int aInt,bInt;
52         for (int i=0;i<len+1;i++)
53         {
54             aInt=i<lenA?A[i]-‘0‘:0;
55             bInt=i<lenB?B[i]-‘0‘:0;
56
57             result[i]=aInt+bInt;
58         }
59
60         //将对应数字结果超过10
61         for (int j=0;j<len+1;j++)
62         {
63             if (result[j]>=10)
64             {
65                 //将对应位置与进位相加，并进行保存
66                 result[j+1]=result[j]/10+result[j+1];
67                 result[j]=result[j]%10;
68             }
69         }
70
71         //将结果对应为0的位置取消掉
72         StringBuilder sb=new StringBuilder();
73         boolean flag=true;//防止结果集中的地位出现0
74         for (int i=len;i>=0;i--)
75         {
76             if (result[i]==0&&flag)
77             {
78
79             }
80             else
81             {
82                 sb.append(result[i]);
83                 flag=false;
84             }
85         }
86
87         return sb.toString();
88         //return result;
89     }
90 }