Project Modules

/*

总结：

    1.不要忘了溢出

    2.单独处理最高位的加法更容易些。

summary:

    1.The overflow of addition of large numbers

    should be noticed.

    2.It's easier to deal with the highest bit

    when adding,I think.

*/

#include <stdio.h>

#include <string.h>

#include <memory.h>

int main()

{

    char srca[1000], srcb[1000];

    int  dsta[1000], dstb[1000], sum[1000];

    int carry = 0;

    while (1)

    {

        memset(dsta, 0x00, sizeof(dsta));

        memset(dstb, 0x00, sizeof(dstb));

        memset(sum , 0x00, sizeof(sum));

        //test if the highest bit has a carry

        //to know the length of "sum" array to be displayed.

        carry = 0;

        //Don't forget test EOF, or I will get

        //time limit exceed.

        if (scanf("%s", srca) == EOF)

        {

            break;

        }

        getchar();

        scanf("%s", srcb);

        getchar();

        int i, j = 999;

        int longer = strlen(srca) > strlen(srcb) ? strlen(srca) : strlen(srcb);

        for (i = strlen(srca)-1; i >= 0; i--)

        {

            dsta[j--] = srca[i] - '0';

        }

        j = 999;

        for (i = strlen(srcb)-1; i >= 0; i--)

        {

            dstb[j--] = srcb[i] - '0';

        }

        for (i = 999; i >= 1; i--)

        {

            sum[i] += dsta[i] + dstb[i];

            if (sum[i] >= 10)

            {

                sum[i]   = sum[i] - 10;

                sum[i-1] += 1;

                if (i == 1000 - longer)

                {

                    carry = 1;

                }

            }

        }

        sum[0] += dsta[0] + dstb[0];

        if (sum[0] >= 10)

        {

            sum[0] = sum[0] - 10;

        }

        if (carry == 1)

            longer++;

        for (i = 1000 - longer; i <1000; i++)

        {

            printf("%d", sum[i]);

        }

        printf("\n");

    }

    return 0;

}