std::basic_filebuf<CharT,Traits>::showmanyc
From cppreference.com
< cpp | io | basic filebuf
protected: virtualstd::streamsize showmanyc() | (optional) | |
If implemented, returns the number of characters left to read from the file.
Contents |
[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.
The name of this function stands for “stream: how many characters?”, so it is pronounced “S how many C", rather than “show many C”.
[edit]Example
An implementation test to see if showmanyc() is implemented for std::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 254
[edit]See also
| obtains the number of characters immediately available in the get area (public member function of std::basic_streambuf<CharT,Traits>) | |
| extracts already available blocks of characters (public member function of std::basic_istream<CharT,Traits>) |
