ACM UVA (10035)

/*
 *******************************************************************************
 *
 * Filename: 10035.c
 *
 * Author: Ye Xiaofeng , yexfeng # gmail.com
 *
 *******************************************************************************
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main(int argc, char **argv)
{
    char buffer1[10];
    char buffer2[10];
    char result_buffer[30];
    char *p1_start, *p2_start;
    char *p2, *p1;
    int num;
    int carray_flag;
    int result;
    int i;

    scanf("%s", &buffer1);
    scanf("%s", &buffer2);
    while (buffer1[0] != '0' || buffer2[0] != '0') {
        p1 = buffer1 + strlen(buffer1) - 1;
        p2 = buffer2 + strlen(buffer2) - 1;
        num = 0;
        while (p1 >= buffer1 || p2 >= buffer2) {
            if (p1 < buffer1) {
                result_buffer[num] = *p2 - '0';
                p2--;
            } else if (p2 < buffer2) {
                result_buffer[num] = *p1 - '0';
                p1--;
            } else {
                result_buffer[num] = *p1 + *p2 - 2 * '0';
                p1--;
                p2--;
            }
            num++;
        }

        carray_flag = 0;
        result = 0;
        for (i = 0; i < num; i++) {
            if (carray_flag + result_buffer[i] >= 10) {
                carray_flag = 1;
                result++;
            } else {
                carray_flag = 0;
            }
        }
        /* Output results */
        if (result == 0) {
            printf("No carry operation.\n");
        } else if (result == 1) {
            printf("1 carry operation.\n");
        } else {
            printf("%d carry operations.\n", result);
        }

        scanf("%s", &buffer1);
        scanf("%s", &buffer2);
    }
}