27 Input/output library [input.output]

27.6 Stream buffers [stream.buffers]

27.6.3 Class template basic_streambuf<charT,traits> [streambuf]

27.6.3.2 basic_streambuf public member functions [streambuf.members]

27.6.3.2.4 Putback [streambuf.pub.pback]

int_type sputbackc(char_type c);

1

Returns: If the input sequence putback position is not available, or if traits::eq(c,gptr()[-1]) is false, returns pbackfail(traits::to_int_type(c)). Otherwise, decrements the next pointer for the input sequence and returns traits::to_int_type(*gptr()).

int_type sungetc();

2

Returns: If the input sequence putback position is not available, returns pbackfail(). Otherwise, decrements the next pointer for the input sequence and returns traits::to_int_type(*gptr()).