java实现大整数相加

/*大整数相加，java实现*/

import java.util.*;

public class Main2 {
public static String str1, str2;
public static int[] c;

public static void main(String[] args) {
// TODO Auto-generated method stub
Scanner sc = new Scanner(System.in);
str1 = sc.next();
str2 = sc.next();
char[] tmp1 = str1.toCharArray();
char[] tmp2 = str2.toCharArray();
int[] array1 = new int[tmp1.length];
int[] array2 = new int[tmp2.length];
// 读取数字
c = new int[(tmp1.length > tmp2.length ? tmp1.length + 1
: tmp2.length + 1)];
for (int i = 0; i < tmp1.length; i++) {
array1[i] = tmp1[i] - '0';
}
for (int i = 0; i < tmp2.length; i++) {
array2[i] = tmp2[i] - '0';
}
// 计算
add(array1, array2);
// 用于去掉前面的0
int result = 0;
for (int i = c.length - 1; i >= 0; i--) {
if (c[i] != 0) {
break;
} else {
result++;
}
}
for (int i = c.length - 1 - result++; i >= 0; i--) {
System.out.print(c[i]);
}
}

// 大整数相加算法
private static void add(int[] array1, int[] array2) {
int r = 0;// 进位
if (array1.length >= array2.length) {
// 第二个数组的下标
int index2 = array1.length - 1;
for (int i = array2.length - 1; i >= 0; i--) {
int index = array2.length - i - 1;
// 相加
c[index] = array1[index2--] + array2[i] + r;
r = c[index] / 10;
c[index] = c[index] % 10;

}
// 把另一个数组全部移动到C数组中
for (int i = array2.length; index2 >= 0; index2--, i++) {
c[i] = array1[index2] + r;
r = c[i] / 10;
c[i] = c[i] % 10;
}

if (r != 0) {
c[c.length - 1] = r;
// System.out.println(c[c.length - 1] + " " + r);
}

} else {
// 第二个数组的下标
int index2 = array2.length - 1;
for (int i = array1.length - 1; i >= 0; i--) {
int index = array1.length - i - 1;
// 相加
c[index] = array2[index2--] + array1[i] + r;
r = c[index] / 10;
c[index] = c[index] % 10;
}
// 把另一个数组全部移动到C数组中
for (int i = array1.length; index2 >= 0; index2--, i++) {
c[i] = array2[index2] + r;
r = c[i] / 10;
c[i] = c[i] % 10;
}
if (r != 0) {
c[c.length - 1] = r;
}
}

}
}