C++ stringstream输入用法

#include<iostream>
#include<string>
#include<sstream>
using namespace std;

int main() {
    string line;
    int k = 1;
    cout<<"------------case 1----------------------"<<endl;
    while(getline(cin, line)) {
    int sum = 0, x;
    stringstream ss(line);
    while(ss >> x) sum += x;
        cout <<"the sum is: " << sum << endl;
        ++k;
        cout<<endl<<"------------case "<<k<<"----------------------"<<endl;
    }
return 0;
}#include<iostream>
#include<string>
#include<ss