C++ Reading fixed number of lines of integers with unknown number of integers in each line

Question

I\'m trying to read in data and solve simple problem, data :

3               - number of lines to read in
1 1
2 2 2
3 4 

after each line is

Answer 1

Read a line at a time, using getline, into an object of type std::string. Then use that std::string object to initialize an object of type std::istringstream, and use an extractor to read int values from the stream object until it fails. Then go back and read the next line. Roughly:

std::string line;
while (std::getline(std::cin, line)) {
    std::istringstream in(line);
    int sum = 0;
    int value = 0;
    while (in >> value)
        sum += value;
    std::cout << sum << '\n';
}

Answer 2

Put

sum=0; // at the top

ps

while(cin.peek()!='\n'){


}

Answer 3

C++ gives you many tools:

• string is a class managing the lifetime of character strings.
• getline puts a line from a stream (up to the next newline) into a string.
• istringstream makes an istream out of a string
• istream_iterator iterates over an istream, extracting the given type, breaking on whitespace.
• accumulate takes iterators delimiting a range and adds together the values:

Altogether:

string line;
while (getline(cin, line)) {
    istringstream in(line);
    istream_iterator<int> begin(in), end;
    int sum = accumulate(begin, end, 0);
    cout << sum << '\n';
}