cin directly to vector<int>, break loop when no more data

Question

The following code runs and stores input in the vector as it should but loops indefinitely listening for input. The intent is to take a string of ints from one line of input, separated by spaces, and store them in a vector.

int main(int argc, char ** argv){
    int input;
    vector<int> intVector;
    while (cin >> input) 
        intVector.push_back(input);
    //print vector contents
    copy(intVector.begin(), intVector.end(), ostream_iterator<char>(cout, " ")); cout << "\n";

    return 0;
}

I want to somehow add a simple, extra condition in the while loop that checks for the end of the line so that it doesn't just keep listening indefinitely. cin.oef is no use here. I've tried that and several other things already.

Is there something clean, short, and elegant that I can add to fix this?

Solution 1

You can use sstream lib:

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

int main(int argc, char ** argv) {

    string buf;

    while(getline(cin, buf)) {

        istringstream ssin(buf);
        vector<int> intVector;
        int input;
        while(ssin >> input) {
            intVector.push_back(input);
        }

        //print vector contents
        cout << intVector.size() << endl;
        copy(intVector.begin(), intVector.end(), ostream_iterator<int>(cout, " "));
        cout << "\n";
    }

    return 0;
}

Solution 2

What about

vector<int> intVector( std::istream_iterator<int>( std::cin ), 
                       std::istream_iterator<int>() );

Comments

[BugShotGG]

nice one! Dont forget to include <iterator> header.

[jww]

Does this meet specifications? What happens with an input of 1 2\n3 4\n. It seems like both lines will be processed instead of the first line.