标准库标头 <istream>

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此头文件是输入/输出库的一部分。

包装给定的抽象设备（std::basic_streambuf）
并提供高层输入接口
(类模板) [编辑]
std::istream std::basic_istream<char>
(typedef)
std::wistream std::basic_istream<wchar_t>
(typedef)
包装给定的抽象设备（std::basic_streambuf）
并提供高层输入/输出接口
(类模板) [编辑]
std::iostream std::basic_iostream<char>
(typedef)
std::wiostream std::basic_iostream<wchar_t>
(typedef)

目录

函数

 提取字符和字符数组
(函数模板) [编辑]
操纵符
消耗空白符
(函数模板) [编辑]

[编辑] 概要

namespace std {
  template<class CharT, class Traits = char_traits<CharT>>
    class basic_istream;
 
  using istream  = basic_istream<char>;
  using wistream = basic_istream<wchar_t>;
 
  template<class CharT, class Traits = char_traits<CharT>>
    class basic_iostream;
 
  using iostream  = basic_iostream<char>;
  using wiostream = basic_iostream<wchar_t>;
 
  template<class CharT, class Traits>
    basic_istream<CharT, Traits>& ws(basic_istream<CharT, Traits>& is);
 
  template<class Istream, class T>
    Istream&& operator>>(Istream&& is, T&& x);
}

[编辑] 类模板 std::basic_istream

namespace std {
  template<class CharT, class Traits = char_traits<CharT>>
  class basic_istream : virtual public basic_ios<CharT, Traits> {
  public:
    // 类型（继承自 basic_ios）
    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;
 
    // 构造函数/析构函数
    explicit basic_istream(basic_streambuf<CharT, Traits>* sb);
    virtual ~basic_istream();
 
    // 前置工序/后置工序
    class sentry;
 
    // 有格式输出
    basic_istream& operator>>(basic_istream& (*pf)(basic_istream&));
    basic_istream& operator>>(basic_ios<CharT, Traits>& (*pf)(basic_ios<CharT, Traits>&));
    basic_istream& operator>>(ios_base& (*pf)(ios_base&));
 
    basic_istream& operator>>(bool& n);
    basic_istream& operator>>(short& n);
    basic_istream& operator>>(unsigned short& n);
    basic_istream& operator>>(int& n);
    basic_istream& operator>>(unsigned int& n);
    basic_istream& operator>>(long& n);
    basic_istream& operator>>(unsigned long& n);
    basic_istream& operator>>(long long& n);
    basic_istream& operator>>(unsigned long long& n);
    basic_istream& operator>>(float& f);
    basic_istream& operator>>(double& f);
    basic_istream& operator>>(long double& f);
 
    basic_istream& operator>>(void*& p);
    basic_istream& operator>>(basic_streambuf<char_type, Traits>* sb);
 
    // 无格式输出
    streamsize gcount() const;
    int_type get();
    basic_istream& get(char_type& c);
    basic_istream& get(char_type* s, streamsize n);
    basic_istream& get(char_type* s, streamsize n, char_type delim);
    basic_istream& get(basic_streambuf<char_type, Traits>& sb);
    basic_istream& get(basic_streambuf<char_type, Traits>& sb, char_type delim);
 
    basic_istream& getline(char_type* s, streamsize n);
    basic_istream& getline(char_type* s, streamsize n, char_type delim);
 
    basic_istream& ignore(streamsize n = 1, int_type delim = Traits::eof());
    int_type       peek();
    basic_istream& read    (char_type* s, streamsize n);
    streamsize     readsome(char_type* s, streamsize n);
 
    basic_istream& putback(char_type c);
    basic_istream& unget();
    int sync();
 
    pos_type tellg();
    basic_istream& seekg(pos_type);
    basic_istream& seekg(off_type, ios_base::seekdir);
 
  protected:
    // 复制/移动构造函数
    basic_istream(const basic_istream&) = delete;
    basic_istream(basic_istream&& rhs);
 
    // 赋值与交换
    basic_istream& operator=(const basic_istream&) = delete;
    basic_istream& operator=(basic_istream&& rhs);
    void swap(basic_istream& rhs);
  };
 
  // 字符提取模板
  template<class CharT, class Traits>
    basic_istream<CharT, Traits>& operator>>(basic_istream<CharT, Traits>&, CharT&);
  template<class Traits>
    basic_istream<char, Traits>& operator>>(basic_istream<char, Traits>&, unsigned char&);
  template<class Traits>
    basic_istream<char, Traits>& operator>>(basic_istream<char, Traits>&, signed char&);
 
  template<class CharT, class Traits, size_t N>
    basic_istream<CharT, Traits>& operator>>(basic_istream<CharT, Traits>&, CharT(&)[N]);
  template<class Traits, size_t N>
    basic_istream<char, Traits>& operator>>(basic_istream<char, Traits>&, unsigned char(&)[N]);
  template<class Traits, size_t N>
    basic_istream<char, Traits>& operator>>(basic_istream<char, Traits>&, signed char(&)[N]);
}

[编辑] 类 std::basic_istream::sentry

namespace std {
  template<class CharT, class Traits>
  class basic_istream<CharT, Traits>::sentry {
    bool ok_;                   // 仅用于阐释
  public:
    explicit sentry(basic_istream& is, bool noskipws = false);
    ~sentry();
    explicit operator bool() const { return ok_; }
    sentry(const sentry&) = delete;
    sentry& operator=(const sentry&) = delete;
  };
}

[编辑] 类模板 std::basic_iostream

namespace std {
  template<class CharT, class Traits = char_traits<CharT>>
  class basic_iostream
    : public basic_istream<CharT, Traits>,
      public basic_ostream<CharT, Traits> {
  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;
 
    // 构造函数
    explicit basic_iostream(basic_streambuf<CharT, Traits>* sb);
 
    // 析构函数
    virtual ~basic_iostream();
 
  protected:
    // 构造函数
    basic_iostream(const basic_iostream&) = delete;
    basic_iostream(basic_iostream&& rhs);
 
    // 赋值与交换
    basic_iostream& operator=(const basic_iostream&) = delete;
    basic_iostream& operator=(basic_iostream&& rhs);
    void swap(basic_iostream& rhs);
  };
}
来自“https://zh.cppreference.com/mwiki/index.php?title=cpp/header/istream&oldid=84216”