How do I take an input in C++ and “split” it into a list? In other words, take N inputs and put in into an array of N length

Question

I'm trying to improve my C++ by doing some Google Kick Start but I can't begin my program because I can't get N inputs. I come from python where this would be exceedingly easy with input().split(), but I have no idea how to do this in C++. I tried googling to find an answer but I cant word my question correctly to where I find the answer. Here is my current code:

#include <iostream>

int main() {
    int t = 0;
    std::cin >> t;
    for (int i = 0; i < t; i++) {
        int n = 0, int k = 0;
        int a[1000];
        std::cin >> n >> k;
        std::cin >> a;
    }
}

, where T is the number of test cases, N is the number of items in the list, K is an argument used to calculate the answer for the contest, and A is the array of N length used to store the values. (The contest is already over, I'm not cheating) It would be nice if someone could help me understand how exactly std::cin works. At first I thought it would be exactly the same as python's input(), but it's different. Thanks.

Answer 1

First of all, there's a typo in your variable declaration. You should only write the type once in the statement, so it should be int n = 0, k = 0; .

The extraction ( >> ) operator only reads single numbers. To take input into an array, you can just write a loop:

int a[1000];
for (int i = 0; i < n; i++)
{
    std::cin >> a[i];
}

This simply reads n numbers and stores them into successive elements in a .

If you want to be fancy, you can use stream iterators:

std::copy_n(std::istream_iterator<int>(std::cin), n, a);

std::istream_iterator<int>(std::cin) constructs a stream iterator which extracts int s from std::cin . std::copy_n then copies n numbers from the stream iterator to a . You need to #include <iterator> and #include <algorithm> in order to use this. You'll probably want to stick with the loop if you don't understand this yet.