大整数的加法

#include <iostream>
#include <string>
using namespace std;

char data1[1001];
char data2[1001];
char sumData[1002];

void main(void)
{
    while (cin >> data1 >> data2)
    {
        int len1 = strlen(data1);
        int len2 = strlen(data2);
        int i = len1 - 1, j = len2 - 1, k = 0;
        int tmp = 0;//进位
        int sum = 0;
        while (i >= 0 && j >= 0)
        {
            sum = (data1[i] - '0') + (data2[j] - '0') + tmp;
            if (sum > 9)
            {
                sum %= 10;
                tmp = 1;
            }
            else
                tmp = 0;
            sumData[k++] = sum + '0';
            i--;
            j--;
        }

        while (i >= 0)
        {
            sum = data1[i] - '0' + tmp;
            if (sum > 9)
            {
                sum %= 10;
                tmp = 1;
            }
            else
                tmp = 0;
            sumData[k++] = sum + '0';
            i--;
        }

        while (j >= 0)
        {
            sum = data2[j] - '0' + tmp;
            if (sum > 9)
            {
                sum %= 10;
                tmp = 1;
            }
            else
                tmp = 0;
            sumData[k++] = sum + '0';
            j--;
        }

        if (tmp == 1)
            sumData[k++] = tmp + '0';
        for (int t = k - 1; t >= 0; t--)
            cout << sumData[t];
        cout << endl;


    }


}