std::istream_iterator::istream_iterator

From cppreference.com
constexpr istream_iterator();
(1)
istream_iterator( istream_type& stream );
(2)
istream_iterator( const istream_iterator& other ) = default;
(3)
1) Constructs the end-of-stream iterator. This constructor is constexpr if std::is_trivially_default_constructible_v<T> is true .
2) Initializes the iterator and stores the address of stream in a data member. Optionally, performs the first read from the input stream to initialize the cached value data member (although it may be delayed until the first access)
3) Constructs a copy of other. If std::is_trivially_copy_constructible_v<T> is true , this copy constructor is a trivial copy constructor.

Parameters

stream - stream to initialize the istream_iterator with
other - another istream_iterator of the same type

Examples

#include <iostream>
#include <iterator>
#include <algorithm>
#include <sstream>
int main()
{
    std::istringstream stream("1 2 3 4 5");
    std::copy(
        std::istream_iterator<int>(stream),
        std::istream_iterator<int>(),
        std::ostream_iterator<int>(std::cout, " ")
    );
}

Output:

1 2 3 4 5