std::istream_iterator::operator++, operator++(int)

From cppreference.com
istream_iterator& operator++();
(1)
istream_iterator operator++(int);
(2)

Reads a value from the underlying stream and stores it into the iterator object.

The behavior is undefined if the iterator is end-of-stream iterator.

Parameters

(none)

Return value

1) *this.
2) An istream_iterator that holds an unchanged value.

Exceptions

(none)