Return how many bytes can be read before underflow may return eof.
Declared in <bdlde_utf8checkinginstreambufwrapper.h>
virtual
std::streamsize
showmanyc() override;Return the number of bytes that are guaranteed that can be read before underflow returns eof. If the object is not in a valid state, -1 will be returned. Note that often, the actual number of bytes that can be read will be much greater than the value returned by this function.
number of bytes guaranteed readable before underflow may return eof, or -1 if this object is not in a valid state