C++进制通用

#include <iostream>
#include <algorithm>

using namespace std;

string conversion(string num, int m, int n)
{
    string ret=""; //栈
    for (unsigned int i = 0; i < num.size();  ) {
        int k = 0;
        for (unsigned int j = i; j < num.size(); ++j) {
            int carry = (k * m + (num[j]-'0')) % n;    
            num[j] = '0' + (k * m + (num[j]-'0')) / n;
            k = carry;
        }
        ret += char( k + '0');
        while (num[i] == '0') i++;
    }    
    reverse(begin(ret),end(ret));
    return ret;
}

int main()
{
    string num;
    while (cin >> num) {
        cout << conversion(num,10,2) << endl;    
    }
    return 0;
}