linux c 实现大数相乘

 

 #include <stdio.h>
 #include <string.h>
 #include <math.h>
 #include <stdbool.h>
 
 #define MAX_LENGTH 128
 #define ASSIST_LENGTH 19
 
 int main(int argc, char **argv)
 {
     unsigned long long data[MAX_LENGTH] = {}, tmp = ;
     int i = , j = , o_len = MAX_LENGTH - ASSIST_LENGTH;
     bool c_flag = true;
 
     if (argc < )
     {
         printf("argument error\n");
         return -;
     }
 
     if (strlen(argv[]) > o_len)
     {
         printf("out of range\n");
         return -;
     }
 
     if (strlen(argv[]) > )
     {
         printf("out of range\n");
         return -;
     }
 
     tmp = atoll(argv[]);
 
     if (9223372036854775807ULL == tmp && ('' == argv[][] || '' == argv[][]))
     {
         printf("out of range\n");
         return -;
     }
 
     for (i = strlen(argv[])-; i >= ; i--)
     {
         data[j] = argv[][i] - ;
         j++;
     }
 
     for (i = o_len - ; i >= ; i--)
     {
         if (c_flag &&  == data[i])
         {
             continue;
         }
 
         c_flag = false;
         printf("%llu", data[i]);
     }
     printf(" * %llu\n", tmp);
 
     for (i = ; i < o_len; i++)
     {
         if ( == data[i])
         {
             continue;
         }
 
         data[i] *= tmp;
     }
 
     for (i = ; i < o_len; i++)
     {
         if ( == data[i])
         {
             continue;
         }
 
         tmp = data[i];
 
         for (j = ASSIST_LENGTH-; j >= ; j--)
         {
             data[i+j] += (tmp / (unsigned long long)pow(,j));
             tmp %= (unsigned long long)pow(,j);
         }
 
         data[i] %= ;
     }
 
     c_flag = true;
     for (i = MAX_LENGTH - ; i >= ; i--)
     {
         if (c_flag &&  == data[i])
         {
             continue;
         }
 
         c_flag = false;
         printf("%llu", data[i]);
     }
     printf("\n");
 
     return ;
 }

实现了任意大数与 2^64-1以下的数相乘，

两个任意大数可以将其中一个拆分成多个因子，

两个大数质数暂未考虑