標準庫標頭檔案 <ios>

 

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標準庫標頭檔案

語言支援 <cfloat> <climits> <compare> (C++20) <contracts> (C++26) <coroutine> (C++20) <csetjmp> <csignal> <cstdarg> <cstddef> <cstdint> (C++11) <cstdlib> <exception> <initializer_list> (C++11)    <limits> <new> <source_location> (C++20) <stdfloat> (C++23) <typeinfo> <version> (C++20) 概念 <concepts> (C++20) 診斷 <cassert> <cerrno> <debugging> (C++26) <stacktrace> (C++23) <stdexcept> <system_error> (C++11) 記憶體管理 <memory> <memory_resource> (C++17) <scoped_allocator> (C++11) 超程式設計 <type_traits> (C++11) <ratio> (C++11)

通用工具 <any> (C++17) <bitset> <bit> (C++20) <charconv> (C++17) <expected> (C++23) <format> (C++20) <functional> <optional> (C++17) <tuple> (C++11) <typeindex> (C++11) <utility> <variant> (C++17) 容器 <array> (C++11) <deque> <flat_map> (C++23) <flat_set> (C++23) <forward_list> (C++11) <hive> (C++26) <inplace_vector> (C++26)    <list> <map> <mdspan> (C++23) <queue> <set> <span> (C++20) <stack> <unordered_map> (C++11) <unordered_set> (C++11) <vector> 迭代器 <iterator> Ranges <generator> (C++23) <ranges> (C++20)

演算法 <algorithm> <numeric> 字串 <cctype> <cstring> <cuchar> (C++11) <cwchar> <cwctype> <string_view> (C++17) <string> 文字處理 <clocale> <codecvt> (C++11/17/26*) <locale> <regex> (C++11) <text_encoding> (C++26)    數值 <cfenv> (C++11) <cmath> <complex> <linalg> (C++26) <numbers> (C++20) <random> (C++11) <simd> (C++26) <valarray> 時間 <chrono> (C++11) <ctime> C 相容性 <ccomplex> (C++11/17/20*) <ciso646> (直到 C++20) <cstdalign> (C++11/17/20*) <cstdbool> (C++11/17/20*) <ctgmath> (C++11/17/20*)

輸入/輸出 <cinttypes> (C++11) <cstdio> <filesystem> (C++17) <fstream> <iomanip> <iosfwd> <iostream> <ios> <istream> <ostream> <print> (C++23) <spanstream> (C++23) <sstream> <streambuf> <strstream> (C++98/26*) <syncstream> (C++20) 併發支援 <atomic> (C++11) <barrier> (C++20) <condition_variable> (C++11) <future> (C++11) <hazard_pointer> (C++26) <latch> (C++20) <mutex> (C++11) <rcu> (C++26) <semaphore> (C++20) <shared_mutex> (C++14) <stdatomic.h> (C++23) <stop_token> (C++20) <thread> (C++11) 執行支援 <execution> (C++17)

 

此標頭檔案是輸入/輸出庫的一部分。

包含
<iosfwd>	輸入/輸出庫中所有類的預宣告
類
ios_base	管理格式化標誌和輸入/輸出異常 (類)
basic_ios	管理任意流緩衝區 (類模板)
std::ios	std::basic_ios<char> (類型別名)
std::wios	std::basic_ios<wchar_t> (類型別名)
fpos	表示流或檔案中的絕對位置 (類模板)
io_errc (C++11)	I/O 流錯誤碼 (列舉)
is_error_code_enum<std::io_errc> (C++11)	擴充套件型別特徵 std::is_error_code_enum 以識別 iostream 錯誤碼 (類模板特化)
streamoff	表示相對檔案/流位置（從 fpos 偏移），足以表示任何檔案大小 (類型別名)
streamsize	表示 I/O 操作中傳輸的字元數或 I/O 緩衝區的大小 (類型別名)
函式
iostream_category (C++11)	標識 iostream 錯誤類別 (函式)
make_error_code(std::io_errc) (C++11)	構造一個 iostream 錯誤碼 (函式)
make_error_condition(std::io_errc) (C++11)	構造一個 iostream 錯誤條件 (函式)
boolalphanoboolalpha	在布林值的文字表示和數字表示之間切換 (函式)
showbasenoshowbase	控制是否使用字首指示數字基數 (函式)
showpointnoshowpoint	控制浮點表示中是否始終包含小數點 (函式)
showposnoshowpos	控制非負數是否使用 + 符號 (函式)
skipwsnoskipws	控制輸入時是否跳過前導空白字元 (函式)
uppercasenouppercase	控制某些輸出格式是否使用大寫字元 (函式)
unitbufnounitbuf	控制每次操作後是否重新整理輸出 (函式)
internalleftright	設定填充字元的位置 (函式)
dechexoct	更改整數 I/O 所用的基數 (函式)
fixedscientifichexfloatdefaultfloat (C++11)(C++11)	更改浮點 I/O 所用的格式 (函式)

概要

#include <iosfwd>
 
namespace std {
  using streamoff  = /* implementation-defined */;
  using streamsize = /* implementation-defined */;
  template<class StateT> class fpos;
 
  class ios_base;
  template<class CharT, class Traits = char_traits<CharT>>
    class basic_ios;
 
  // manipulators
  ios_base& boolalpha  (ios_base& str);
  ios_base& noboolalpha(ios_base& str);
 
  ios_base& showbase   (ios_base& str);
  ios_base& noshowbase (ios_base& str);
 
  ios_base& showpoint  (ios_base& str);
  ios_base& noshowpoint(ios_base& str);
 
  ios_base& showpos    (ios_base& str);
  ios_base& noshowpos  (ios_base& str);
 
  ios_base& skipws     (ios_base& str);
  ios_base& noskipws   (ios_base& str);
 
  ios_base& uppercase  (ios_base& str);
  ios_base& nouppercase(ios_base& str);
 
  ios_base& unitbuf    (ios_base& str);
  ios_base& nounitbuf  (ios_base& str);
 
  // adjustfield
  ios_base& internal   (ios_base& str);
  ios_base& left       (ios_base& str);
  ios_base& right      (ios_base& str);
 
  // basefield
  ios_base& dec        (ios_base& str);
  ios_base& hex        (ios_base& str);
  ios_base& oct        (ios_base& str);
 
  // floatfield
  ios_base& fixed      (ios_base& str);
  ios_base& scientific (ios_base& str);
  ios_base& hexfloat   (ios_base& str);
  ios_base& defaultfloat(ios_base& str);
 
  // error reporting
  enum class io_errc {
    stream = 1
  };
 
  template<> struct is_error_code_enum<io_errc> : public true_type { };
  error_code make_error_code(io_errc e) noexcept;
  error_condition make_error_condition(io_errc e) noexcept;
  const error_category& iostream_category() noexcept;
}

類 std::ios_base

namespace std {
  class ios_base {
  public:
    class failure;              // see description
 
    // fmtflags
    using fmtflags = /*bitmask-type-1*/;
    static constexpr fmtflags boolalpha = /* unspecified */;
    static constexpr fmtflags dec = /* unspecified */;
    static constexpr fmtflags fixed = /* unspecified */;
    static constexpr fmtflags hex = /* unspecified */;
    static constexpr fmtflags internal = /* unspecified */;
    static constexpr fmtflags left = /* unspecified */;
    static constexpr fmtflags oct = /* unspecified */;
    static constexpr fmtflags right = /* unspecified */;
    static constexpr fmtflags scientific = /* unspecified */;
    static constexpr fmtflags showbase = /* unspecified */;
    static constexpr fmtflags showpoint = /* unspecified */;
    static constexpr fmtflags showpos = /* unspecified */;
    static constexpr fmtflags skipws = /* unspecified */;
    static constexpr fmtflags unitbuf = /* unspecified */;
    static constexpr fmtflags uppercase = /* unspecified */;
    static constexpr fmtflags adjustfield = /* see description */;
    static constexpr fmtflags basefield = /* see description */;
    static constexpr fmtflags floatfield = /* see description */;
 
    // iostate
    using iostate = /*bitmask-type-2*/;
    static constexpr iostate badbit = /* unspecified */;
    static constexpr iostate eofbit = /* unspecified */;
    static constexpr iostate failbit = /* unspecified */;
    static constexpr iostate goodbit = /* see description */;
 
    // openmode
    using openmode = /*bitmask-type-3*/;
    static constexpr openmode app = /* unspecified */;
    static constexpr openmode ate = /* unspecified */;
    static constexpr openmode binary = /* unspecified */;
    static constexpr openmode in = /* unspecified */;
    static constexpr openmode out = /* unspecified */;
    static constexpr openmode trunc = /* unspecified */;
    static constexpr openmode noreplace = /* unspecified */
 
    // seekdir
    using seekdir = /*bitmask-type-4*/;
    static constexpr seekdir beg = /* unspecified */;
    static constexpr seekdir cur = /* unspecified */;
    static constexpr seekdir end = /* unspecified */;
 
    class Init;
 
    // fmtflags state
    fmtflags flags() const;
    fmtflags flags(fmtflags fmtfl);
    fmtflags setf(fmtflags fmtfl);
    fmtflags setf(fmtflags fmtfl, fmtflags mask);
    void unsetf(fmtflags mask);
 
    streamsize precision() const;
    streamsize precision(streamsize prec);
    streamsize width() const;
    streamsize width(streamsize wide);
 
    // locales
    locale imbue(const locale& loc);
    locale getloc() const;
 
    // storage
    static int xalloc();
    long&  iword(int idx);
    void*& pword(int idx);
 
    // destructor
    virtual ~ios_base();
 
    // callbacks
    enum event { erase_event, imbue_event, copyfmt_event };
    using event_callback = void (*)(event, ios_base&, int idx);
    void register_callback(event_callback fn, int idx);
 
    ios_base(const ios_base&) = delete;
    ios_base& operator=(const ios_base&) = delete;
 
    static bool sync_with_stdio(bool sync = true);
 
  protected:
    ios_base();
 
  private:
    static int index;           // exposition only
    long*  iarray;              // exposition only
    void** parray;              // exposition only
  };
}

類 std::ios_base::failure

namespace std {
  class ios_base::failure : public system_error {
  public:
    explicit failure(const string& msg, const error_code& ec = io_errc::stream);
    explicit failure(const char* msg, const error_code& ec = io_errc::stream);
  };
}

類 std::ios_base::Init

namespace std {
  class ios_base::Init {
  public:
    Init();
    Init(const Init&) = default;
    ~Init();
    Init& operator=(const Init&) = default;
  private:
    static int init_cnt;        // exposition only
  };
}

類模板 std::fpos

namespace std {
  template<class StateT> class fpos {
  public:
    // members
    StateT state() const;
    void state(stateT);
  private;
    StateT st;                  // exposition only
  };
}

類模板 std::basic_ios

namespace std {
  template<class CharT, class Traits = char_traits<CharT>>
  class basic_ios : public ios_base {
  public:
    using char_type   = CharT;
    using int_type    = typename Traits::int_type;
    using pos_type    = typename Traits::pos_type;
    using off_type    = typename Traits::off_type;
    using traits_type = Traits;
 
    // flags functions
    explicit operator bool() const;
    bool operator!() const;
    iostate rdstate() const;
    void clear(iostate state = goodbit);
    void setstate(iostate state);
    bool good() const;
    bool eof()  const;
    bool fail() const;
    bool bad()  const;
 
    iostate exceptions() const;
    void exceptions(iostate except);
 
    // constructor/destructor
    explicit basic_ios(basic_streambuf<CharT, Traits>* sb);
    virtual ~basic_ios();
 
    // members
    basic_ostream<CharT, Traits>* tie() const;
    basic_ostream<CharT, Traits>* tie(basic_ostream<CharT, Traits>* tiestr);
 
    basic_streambuf<CharT, Traits>* rdbuf() const;
    basic_streambuf<CharT, Traits>* rdbuf(basic_streambuf<CharT, Traits>* sb);
 
    basic_ios& copyfmt(const basic_ios& rhs);
 
    char_type fill() const;
    char_type fill(char_type ch);
 
    locale imbue(const locale& loc);
 
    char      narrow(char_type c, char dfault) const;
    char_type widen(char c) const;
 
    basic_ios(const basic_ios&) = delete;
    basic_ios& operator=(const basic_ios&) = delete;
 
  protected:
    basic_ios();
    void init(basic_streambuf<CharT, Traits>* sb);
    void move(basic_ios& rhs);
    void move(basic_ios&& rhs);
    void swap(basic_ios& rhs) noexcept;
    void set_rdbuf(basic_streambuf<CharT, Traits>* sb);
  };
}

缺陷報告

下列更改行為的缺陷報告追溯地應用於以前出版的 C++ 標準。

缺陷報告	應用於	釋出時的行為	正確的行為
LWG 35	C++98	在概要中缺少 unitbuf 和 nounitbuf 的原型	已新增
LWG 78	C++98	ios_base::register_callback 的引數 fn 的型別 在概要中被錯誤指定為 event_call_back	更正為 event_callback