< cpp‎ | io‎ | basic filebuf
virtual std::streamsize showmanyc()

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


[edit] Parameters


[edit] Return value

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

[edit] 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.

[edit] Example

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

#include <fstream>
#include <iostream>
struct mybuf : std::filebuf
     using std::filebuf::showmanyc;
int main()
    mybuf fin;"", std::ios_base::in);
    std::cout << "showmanyc() returns " << fin.showmanyc() << '\n';


showmanyc() returns 6626

[edit] See also

obtains the number of characters immediately available in the get area
(public member function of std::basic_streambuf)
extracts already available blocks of characters
(public member function of std::basic_istream)