关于输入结束EOF

#include <iostream>
#include <fstream>
#include <string>

using namespace std;

int main()
{
    int sum = 0;
   
    if(!cin.good())
    {
        cout<<"input bad!"<<endl;
        exit(1);
    }
   
    int number;
   
    while(1)
    {
        cin>>number;
      
        if(cin.good())
        {
            sum += number;
        }
        else if(cin.eof())
        {
            break;
        }
        else
        {
            cin.clear();
            string badtoken;
            getline(cin, badtoken);
            cerr<<"warning!"<<badtoken<<endl;
        }
    }
   
    cout<<"sum is"<<sum<<endl;
   
    return 0;
}