C++ 一个超大的10进制数转2进制算法

#include 
#include 
#include 

using namespace std;

//convert decimal to Binary
void shiToEr(string s) {
	int sum(0);
	vectorv;
	int i, j;
	string binary;
	char ch;

	//把每一位存到v里面去 
	for (int i(s.length() - 1); i >= 0; --i) {
		v.insert(v.begin(), s[i] - '0');
	}

	//计算二进制 
	while (1) {
		j = v.size() - 1;
		ch = v[j] % 2 + '0';
		binary.insert(binary.begin(), 1, ch);
		for (sum = 0, i = 0; i <= j; i++) {
			if (i < j) {				
				v[i + 1] += (v[i] - ((v[i] >> 1) << 1)) * 10;
			}
			
			v[i] >>= 1;
			sum += v[i];
		}
		if (sum == 0) {
			break;
		}
	}
	cout << binary << endl;
}

int main() {
	string dec;
	while (cin >> dec) {
		shiToEr(dec);
	}
	return 0;
}