c++标准异常使用和<<运算符重载示例

#include <iostream>
#include <stdexcept>

using namespace std;


class Data
{
public:
    Data(int a,int b):y(a),m(b)
    {
        if(b < 1 || b > 12) throw(logic_error("Error:...") );
    }
    friend ostream & operator<<(ostream & os,Data x)
    {
        cout << x.y << x.m << endl;
        return os;
    }
private:
    int y{1970};
    int m{1};
};

int main()
{
    Data d(2015,19);
    cout << d;
    return 0;
}