十进制转为N进制

昨天笔试遇到的题，如果是正数，不断以余数做除法即可：

void convert(int num, int N, vector<char>& data)
{
    int number = num;
    //if (num < 0)
//        num = -num;
    while (num != 0)
    {
        int temp = num%N;
        if (temp <= 9)
            data.push_back(temp + ‘0‘);
        else
            data.push_back(temp - 10 + ‘A‘);
        num /= N;
    }
    //if (number < 0)
    //    data.push_back(‘-‘);
}

int main()
{
    int num, N;
    while (cin >> num >> N)
    {
        if (N == 10)
        {
            cout << num << endl;
            continue;
        }
        vector<char> data;
        convert(num, N, data);

        for (int i = data.size() - 1; i >= 0; i--)
        {
            cout << data[i];
        }
        cout << endl;
    }
    return 0;
}

如果是负数怎么办呢？