Read X number of lines with an indeterminate number of integers

input_lines_of_numbers.cpp

#include <iostream>
#include <vector>
#include <string>
#include <sstream>
#include <iterator>

int main()
{
    size_t number_of_rows;
    std::cout << "Enter the number of rows: ";
    std::cin >> number_of_rows;

    // Create vectors of vectors
    std::vector<std::vector<int>> rows_of_numbers(number_of_rows);

    // Skip the newline from the previous input
    std::cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n');

    // Now read each line
    for (auto &row : rows_of_numbers)
    {
        // Read the line
        std::string line;
        std::getline(std::cin, line);

        // Parse each line into a sequence of numbers
        std::istringstream iss(line);
        row = std::vector<int>(std::istream_iterator<int>(iss), std::istream_iterator<int>());
    }

    // Display each row
    for (auto const &row : rows_of_numbers)
    {
        for (auto const value : row)
        {
            std::cout << value << ' ';
        }

        std::cout << '\n';
    }
}