wcerr

Library:  Input/output

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A predefined stream that controls output to an unbuffered stream buffer associated with the object stderr declared in <cstdio>

#include <iostream>

namespace std {
  extern wostream wcerr;
}

The object wcerr 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.

wcerr uses the locale codecvt facet to convert the wide characters it receives to the tiny characters it outputs to stderr.

The formatting is done through member functions or manipulators. See cout, wcout, or basic_ostream for details.

//
// wcerr example
//
#include <iostream>
#include <fstream>

void main ( )
{
  using namespace std;
   
  // open the file "file_name.txt"
  // for reading
  wifstream in("file_name.txt");
  
  // output the all file to stdout
  if ( in ) 
    wcout << in.rdbuf(); 
  else
    // if the wifstream object is in a bad state
    // output an error message to stderr
    wcerr << L"Error while opening the file" << endl;  
}

basic_ostream, basic_iostream, basic_filebuf, cout, cin, cerr, clog, wcin, wcout, wclog, ios_base, basic_ios

ISO/IEC 14882:1998 -- International Standard for Information Systems --Programming Language C++, Section 27.3.2