std::basic_filebuf<CharT,Traits>::showmanyc - cppreference.com (original) (raw)

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

[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.

#include #include   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:

[edit] See also

| | obtains the number of characters immediately available in the get area (public member function of std::basic_streambuf<CharT,Traits>) [edit] | | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | | extracts already available blocks of characters (public member function of std::basic_istream<CharT,Traits>) [edit] |