打印出一串数字

程序如下：

#include <iostream>

using namespace std;
class Solution
{
public:
	int myatoi(string str)
	{
		const int maxint = 0x7fffffff;
		const int minint = 0x80000000;
		long long ans = 0;
		int st = 0;
		bool flag = false;

		while (st < str.length() && str[st] == ' ')
		{
			st++;
		}
		if (st < str.length() && str[st] == '+') st++;
		if (st < str.length() && str[st] == '-'){
			flag = true;
			st++;
		}
		for (int i = 0; i < str.length();i++)
		{
			if (str[i]<='9'&&str[i]>='0')
			{
				ans = ans * 10 + str[i] - '0';
				if (ans>maxint) ans = maxint;
			}
			else{
				break;
			}
		}
		if (flag) ans = -ans;
		if (ans > maxint) ans = maxint;
		if (ans < minint) ans = minint;
		return ans;
	}
};


int main()
{
	Solution S;
	string str("999999");
	int y;
	y=S.myatoi(str);
	cout << "y=" << y << endl;
	return 0;
}