std::basic_streambuf<CharT,Traits>::showmanyc

protected:
virtual std::streamsize showmanyc();

Estimates the number of characters available for input in the associated character sequence. underflow() is guaranteed not to return Traits::eof() or throw an exception until at least that many characters are extracted.

Parameters

(none).

Return value

The number of characters that are certainly available in the associated character sequence, or -1 if showmanyc can determine, without blocking, that no characters are available. If showmanyc returns -1, underflow() and uflow() will definitely return Traits::eof or throw.

The base class version returns ​0​, which has the meaning of "unsure if there are characters available in the associated sequence".

Notes

The name of this function stands for "stream: how many characters?", so it is pronounced "S how many C", rather than "show many C".

Example

Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

See also