Pre-defined stream
Controls output to an unbuffered stream buffer associated with the object stderr declared in <cstdio>.
None
#include <iostream> extern ostream cerr; ostream cerr;
The object cerr controls output to an unbuffered stream buffer associated with the object stderr declared in <cstdio>. By default, the standard C and C++ streams are synchronized, but you can improve performance by using the ios_base member function synch_with_stdio to desynchronize them.
The formatting is done through member functions or manipulators. See cout or basic_ostream for details.
// // cerr example // #include<iostream> #include<fstream> void main ( ) { using namespace std; // open the file "file_name.txt" // for reading ifstream in("file_name.txt"); // output the all file to stdout if ( in ) cout << in.rdbuf(); else // if the ifstream object is in a bad state // output an error message to stderr cerr << "Error while opening the file" << endl; }
basic_ostream(3C++), iostream(3C++), basic_filebuf(3C++), cout(3C++), cin(3C++), clog(3C++), wcin(3C++), wcout(3C++), wcerr(3C++), iomanip(3C++), wclog(3C++), ios_base(3C++), basic_ios(3C++)
Working Paper for Draft Proposed International Standard for Information Systems--Programming Language C++, Section 27.3.1
ANSI X3J16/ISO WG21 Joint C++ Committee