libstdc++
iostream
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1 // Standard iostream objects -*- C++ -*-
2 
3 // Copyright (C) 1997-2025 Free Software Foundation, Inc.
4 //
5 // This file is part of the GNU ISO C++ Library. This library is free
6 // software; you can redistribute it and/or modify it under the
7 // terms of the GNU General Public License as published by the
8 // Free Software Foundation; either version 3, or (at your option)
9 // any later version.
10 
11 // This library is distributed in the hope that it will be useful,
12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 // GNU General Public License for more details.
15 
16 // Under Section 7 of GPL version 3, you are granted additional
17 // permissions described in the GCC Runtime Library Exception, version
18 // 3.1, as published by the Free Software Foundation.
19 
20 // You should have received a copy of the GNU General Public License and
21 // a copy of the GCC Runtime Library Exception along with this program;
22 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23 // <http://www.gnu.org/licenses/>.
24 
25 /** @file include/iostream
26  * This is a Standard C++ Library header.
27  */
28 
29 //
30 // ISO C++ 14882: 27.3 Standard iostream objects
31 //
32 
33 #ifndef _GLIBCXX_IOSTREAM
34 #define _GLIBCXX_IOSTREAM 1
35 
36 #ifdef _GLIBCXX_SYSHDR
37 #pragma GCC system_header
38 #endif
39 
40 #include <bits/requires_hosted.h> // iostreams
41 
42 #include <bits/c++config.h>
43 #include <ostream>
44 #include <istream>
45 
46 namespace std _GLIBCXX_VISIBILITY(default)
47 {
48 _GLIBCXX_BEGIN_NAMESPACE_VERSION
49 
50  /**
51  * @name Standard Stream Objects
52  *
53  * The `<iostream>` header declares the eight *standard stream objects*.
54  * For other declarations, see
55  * https://gcc.gnu.org/onlinedocs/libstdc++/manual/io.html
56  * and the @link iosfwd I/O forward declarations @endlink
57  *
58  * They are required by default to cooperate with the global C
59  * library's `FILE` streams, and to be available during program
60  * startup and termination. For more information, see the section of the
61  * manual linked to above.
62  */
63  ///@{
64  extern istream cin; ///< Linked to standard input
65  extern ostream cout; ///< Linked to standard output
66  extern ostream cerr; ///< Linked to standard error (unbuffered)
67  extern ostream clog; ///< Linked to standard error (buffered)
68 
69 #ifdef _GLIBCXX_USE_WCHAR_T
70  extern wistream wcin; ///< Linked to standard input
71  extern wostream wcout; ///< Linked to standard output
72  extern wostream wcerr; ///< Linked to standard error (unbuffered)
73  extern wostream wclog; ///< Linked to standard error (buffered)
74 #endif
75  ///@}
76 
77  // For construction of filebuffers for cout, cin, cerr, clog et. al.
78  // When the init_priority attribute is usable, we do this initialization
79  // in the compiled library instead (src/c++98/globals_io.cc).
80 #if !(_GLIBCXX_USE_INIT_PRIORITY_ATTRIBUTE \
81  && __has_attribute(__init_priority__))
82  static ios_base::Init __ioinit;
83 #elif defined(_GLIBCXX_SYMVER_GNU) && defined(__ELF__)
84  __extension__ __asm (".globl _ZSt21ios_base_library_initv");
85 #endif
86 
87 _GLIBCXX_END_NAMESPACE_VERSION
88 } // namespace
89 
90 #endif /* _GLIBCXX_IOSTREAM */