std::istreambuf_iterator<CharT,Traits>::operator++, operator++(int) - cppreference.com

istreambuf_iterator& operator++();

/* proxy */ operator++( int );

Advances the iterator by calling sbuf_->sbumpc() where sbuf_ is the stored pointer to the stream buffer.

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

Parameters

(none)

Return value

1) *this

2) A proxy object holding the current character obtained via operator*() and the sbuf_ pointer. Dereferencing a proxy object with operator* yields the stored character.

The name proxy is for exposition only.

Exceptions

May throw implementation-defined exceptions.