M进制转N进制

算法思路：取余，再将余数逆序

#include <stdio.h>

void m2n(int m, char* mNum, int n, char* nNum)
{
      int i = 0;
      char c, *p = nNum;

      while(*mNum != '\0')
      {
            i = i * m + *mNum - '0';
            mNum ++;
      }

      while(i)
      {
            *p = i % n + '0';
            i /= n;
            p ++;
      }
      *p = '\0';
      p --;

      while(p > nNum)
      {
            c = *p;
            *p = *nNum;
            *nNum = c;
            p --;
            nNum ++;
      }
}
int main(int argc, char* argv[])
{
      int m = 10;
      int n = 5;
      char* mNum = "8";
      char nNum[50] = {0};
      m2n(m, mNum, n, nNum);
      printf("%s", nNum);
}