std::istreambuf_iterator::istreambuf_iterator

From cppreference.com
constexpr istreambuf_iterator();
(1)
istreambuf_iterator( std::basic_istream<CharT,Traits>& is );
(2)
istreambuf_iterator( std::basic_streambuf<CharT,Traits>* s );
(3)
istreambuf_iterator(const istreambuf_iterator&) noexcept = default;
(4) (since C++11)
1) Constructs the end-of-stream iterator.
2) Initializes the iterator and stores the address of is.rdbuf() in a data member. If is.rdbuf() is null, then end-of-stream iterator is constructed.
3) Initializes the iterator and stores the address of s in a data member.
4) Default copy constructor

[edit] Parameters

is - stream to obtain the stream buffer from
s - stream buffer to initialize the iterator with

[edit] Exceptions

1-4)
noexcept specification:  
noexcept