任意进制间的转换

以前只是研究某两个进制A，B之间的转化，现在推广到任意进制。

其中十进制转为B进制：除B取余，倒序排列
目前的缺点是不能算小数和负数。

#include <bits/stdc++.h>using namespace std;int toTen(const string & old, const int base){    int res = 0;    for(size_t i = 0; i != old.length(); i++) {        if(isupper(old[i])) res = res * base + old[i] - 'A' + 10;        else if(islower(old[i])) res = res * base + old[i] - 'a' + 10;        else res = res * base + old[i] - '0';    }    return res;}deque<char> Tento(int ten, const int base){    deque<char> res;    while(ten > 0){        int t = ten % base;        res.push_front(t>=10 ? (char)(t-10+'A') : (char)(t+'0'));        ten /= base;    }    return res;}int main(){    int x, y, ten; string old;    printf("输入原数：");  cin >> old;    printf("输入原数进制：");  cin >> x;    printf("输入要转换到的进制：");  cin >> y;    ten = toTen(old, x);    deque<char> res = Tento(ten, y);    for(size_t i = 0; i != res.size(); i++)        printf("%c", res[i]);    printf("\n");    return 0;}