How to read in user entered comma separated integers?

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All of the existing answers are excellent, but all are specific to your particular task. Ergo, I wrote a general touch of code that allows input of comma separated values in a standard way:

template<class T, char sep=','>
struct comma_sep { //type used for temporary input
    T t; //where data is temporarily read to
    operator const T&() const {return t;} //acts like an int in most cases
};
template<class T, char sep>
std::istream& operator>>(std::istream& in, comma_sep<T,sep>& t) 
{
    if (!(in >> t.t)) //if we failed to read the int
        return in; //return failure state
    if (in.peek()==sep) //if next character is a comma
        in.ignore(); //extract it from the stream and we're done
    else //if the next character is anything else
        in.clear(); //clear the EOF state, read was successful
    return in; //return 
}

Sample usage http://coliru.stacked-crooked.com/a/a345232cd5381bd2:

typedef std::istream_iterator<comma_sep<int>> istrit; //iterators from the stream
std::vector<int> vec{istrit(in), istrit()}; //construct the vector from two iterators

Since you’re a beginner, this code might be too much for you now, but I figured I’d post this for completeness.

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