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std::basic_...f::showmanyc(3)  C++ Standard Libary std::basic_...f::showmanyc(3)

NAME
     std::basic_filebuf::showmanyc - std::basic_filebuf::showmanyc

Synopsis
	protected:
	virtual std::streamsize showmanyc()

	If  implemented,  returns the number of characters left to read from the
     file.

Parameters
	(none)

Return value
	The number of characters available for reading from the file, or  -1  if
     the end of
	file was reached.

Notes
	This  function	is optional. If not implemented, this function returns 0
     (since the
	base class version std::basic_streambuf::showmanyc gets called)

	Whether implemented or not, this function is normally called by
	std::basic_streambuf::in_avail if the get area is empty.

	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
	implementation test to see if showmanyc() is implemented for filebuf

     // Run this code

      #include <fstream>
      #include <iostream>

      struct mybuf : std::filebuf
      {
	   using std::filebuf::showmanyc;
      };

      int main()
      {
	  mybuf fin;
	  fin.open("main.cpp", std::ios_base::in);
	  std::cout << "showmanyc() returns " << fin.showmanyc() << '\n';
      }

Possible output:
      showmanyc() returns 267

See also
	in_avail  obtains  the number of characters immediately available in the
     get area
		 (public member function of std::basic_streambuf<CharT,Traits>)
	readsome extracts already available blocks of characters
		 (public member function of std::basic_istream<CharT,Traits>)

http://cppreference.com 	   2024.06.10	   std::basic_...f::showmanyc(3)
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