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

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

#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';
}

showmanyc() returns 267

See also