大数相加, 大数相乘

  没怎么测试, 有BUG请提出, 注意加法时参数1要大于等于参数2, 乘法无限制

#include <stdio.h>#include <string.h>#include <malloc.h>//len1 >= len2char *Add(const char *param1, const char *param2, int len1, int len2){int i = 0;int j = 0;char *res = (char*)malloc((len1+2)*sizeof(char));memset(res, 0, len1+2);for (i=len1-1; i>=0; --i)res[i+1] += param1[i] - 0x30;for (i=len1, j=len2-1; j>=0; --j, --i){res[i] += param2[j] - 0x30;if (res[i] > 9){res[i-1] += 1;res[i] -= 10;}}if (res[1] > 9){res[0] += 1;res[1] -= 10;}for (i=0; i<=len1; ++i)res[i] += 0x30;if (res[0] == 0x30)for (i=0; res[i]!='/0'; ++i)res[i] = res[i+1];return res;}//no limit while len1>len2 or len1<len2char *Multi(char *param1, char *param2, int len1, int len2){char *res = (char*)malloc((len1+len2+1)*sizeof(char));memset(res, 0, (len1+len2+1)*sizeof(char));int i = 0;int j = 0;int k = 0;int m = 0;int n = 0;for (i=len1-1, k=len1+len2-1; i>=0; --i, --k){m = k;for (j=len2-1; j>=0; --j){res[m] += (param1[i] - 0x30) * (param2[j] - 0x30);n = res[m]/10;if (n > 0){res[m-1] += n;res[m] -=10*n;}--m;}}for (i=0; i<=len1+len2-1; ++i)res[i] += 0x30;if (res[0] == 0x30)for (i=0; res[i]!='/0'; ++i)res[i] = res[i+1];return res;}int main(){char ch1 = '4';char ch2 = '7';char ch3 = ch1 - 0x30 + ch2 - 0x30;printf("%c, %c, %d,/n", ch1, ch2, ch3);//打出a对应的ascii码printf("----------/n");char param1[100] = "9999";char param2[100] = "999";int len1 = strlen(param1);int len2 = strlen(param2);printf("%s, %s/n", Add(param1, param2, len1, len2), Multi(param1, param2, len1, len2));return 0;}