1. #include <stdio.h>
    2. #include <string.h>
    3. #define N 500
    5. void BigNumAdd(char *n1, char *n2){
    6.     char result[N], *p1, *p2, *p3 = result, temp;
    7.     int n = 0, rn1, rn2, i;
    8.     //p1、p2分别指向n1、n2的个位数
    9.     p1 = n1+(strlen(n1)-1)*sizeof(char);
    10.     p2 = n2+(strlen(n2)-1)*sizeof(char);
    11.     while (p1 >= n1 || p2 >= n2){
    12.         //获取真实数值
    13.         rn1 = p1 >= n1 ? *p1-'0' : 0;
    14.         rn2 = p2 >= n2 ? *p2-'0' : 0;
    15.         //保留个位
    16.         *p3 = (rn1+rn2+n) % 10 + '0';
    17.         n = (rn1+rn2+n) >= 10 ? 1 : 0;
    18.         p1--;
    19.         p2--;
    20.         p3++;
    21.     }
    22.     if(n){
    23.         *p3 = '1';
    24.         p3++;
    25.     }
    26.     *p3 = '\0';
    27.     for(i = 0; i < strlen(result) / 2; i++){
    28.         temp = result[i];
    29.         result[i] = result[strlen(result)-i-1];
    30.         result[strlen(result)-i-1] = temp;
    31.     }
    32.     printf("%s\n", result);
    33. }
    35. int main(int argc, char *argv[]) {
    36.     BigNumAdd("12311", "100211");
    37.     return 0;
    38. }