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Standard library header <iostream>

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This header is part of the Input/output library.

Including <iostream> behaves as if it defines a static storage duration object of type std::ios_base::Init , whose constructor initializes the standard stream objects if it is the first std::ios_base::Init object to be constructed, and whose destructor flushes those objects (except for cin and wcin) if it is the last std::ios_base::Init object to be destroyed.

Contents

Includes

(C++11)

std::ios_base class, std::basic_ios class template and typedefs[edit]

(C++11)

std::basic_streambuf class template[edit]

(C++11)

std::basic_istream class template and typedefs[edit]

(C++11)

std::basic_ostream , std::basic_iostream class templates and typedefs[edit]

Objects

reads from the standard C input stream stdin
(global object)[edit]

writes to the standard C output stream stdout
(global object)[edit]

writes to the standard C error stream stderr , unbuffered
(global object)[edit]

writes to the standard C error stream stderr
(global object)[edit]

[edit] Synopsis

#include <ios>
#include <streambuf>
#include <istream>
#include <ostream>
 
namespace std {
 extern istream cin;
 extern ostream cout;
 extern ostream cerr;
 extern ostream clog;
 
 extern wistream wcin;
 extern wostream wcout;
 extern wostream wcerr;
 extern wostream wclog;
}

[edit] Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR	Applied to	Behavior as published	Correct behavior
LWG 155	C++98	the type of the static object was `std::basic_ios::Init` (not strictly wrong, but the wording was misleading)	corrected to `std::ios_base::Init`
LWG 1123	C++98	including `<iostream>` did not guarantee the construction of std::ios_base::Init objects	guarantees

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