标准库头文件 <istream>

 

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标准库头文件

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正则表达式库 (C++11)

原子操作库 (C++11)

线程支持库 (C++11)

文件系统库 (C++17)

技术规范

 

标准库头文件

语言支持
<cstddef> <limits> <climits> <coroutine>	<cfloat> <cstdint> <new> <source_location>	<typeinfo> <exception> <initializer_list> <version>	<csignal> <csetjmp> <cstdarg>
概念
<concepts>
诊断
<stdexcept>	<cassert>	<cerrno>	<system_error>
通用工具
<utility> <memory> <memory_resource> <scoped_allocator>     <compare>	<bitset> <tuple> <optional> <any> <variant>	<type_traits> <ratio> <chrono> <typeindex> <functional>	<ctime> <cstdlib>
字符串
<string> <string_view> <cstring>	<charconv> <format>	<cctype> <cwctype>	<cwchar> <cuchar>
本地化
<locale>	<codecvt>	<clocale>
容器
<span> <array> <vector>	<deque> <forward_list> <list>	<map> <set> <queue>	<unordered_map> <unordered_set> <stack>
迭代器
<iterator>
范围
<ranges>
算法
<algorithm>	<execution>
数值
<complex> <random>	<valarray> <numeric>	<bit> <numbers>	<cfenv> <cmath>
输入/输出
<iosfwd> <ios> <iomanip> <streambuf>	<istream> <ostream> <iostream>	<sstream> <fstream> <syncstream>	<cstdio> <cinttypes> <strstream>
正则表达式
<regex>
文件系统
<filesystem>
线程支持
<thread> <atomic> <mutex>	<shared_mutex> <condition_variable> <future>	<stop_token> <semaphore>	<latch> <barrier>
C 兼容
<ciso646> <cstdalign>	<cstdbool> <ccomplex>	<ctgmath>

 

此头文件是输入/输出库的一部分。

basic_istream	包装给定的抽象设备（std::basic_streambuf） 并提供高层输入接口 (类模板)
std::istream	basic_istream<char> (typedef)
std::wistream	basic_istream<wchar_t> (typedef)
basic_iostream	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)
std::iostream	basic_iostream<char> (typedef)
std::wiostream	basic_iostream<wchar_t> (typedef)
函数
operator>>(std::basic_istream)	提取字符和字符数组 (函数模板)
操纵符
ws	消耗空白符 (函数模板)

概要

namespace std {
    template <class charT, class traits = char_traits<charT> >
        class basic_istream;
    typedef basic_istream<char>    istream;
    typedef basic_istream<wchar_t> wistream;
 
    template <class charT, class traits = char_traits<charT> >
        class basic_iostream;
    typedef basic_istream<char>    iostream;
    typedef basic_istream<wchar_t> wiostream;
 
    template <class charT, class traits>
        basic_istream<charT,traits>& ws(basic_istream<charT,traits>& is);
 
    template <class charT, class traits, class T>
        basic_istream<charT, traits>&
        operator>>(basic_istream<charT, traits>&& is, T& x);
 
    // 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>
        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*);
 
}

类 std::basic_istream

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）：
    typedef charT                     char_type;
    typedef typename traits::int_type int_type;
    typedef typename traits::pos_type pos_type;
    typedef typename traits::off_type off_type;
    typedef traits                    traits_type;
 
    // 构造函数/析构函数：
    explicit basic_istream(basic_streambuf<char_type,traits>* sb);
    virtual ~basic_istream();
 
    // 前缀/后缀：
    class sentry;
 
    // 有格式输入：
    basic_istream<charT,traits>& operator>>(
        basic_istream<charT,traits>& (*pf)(basic_istream<charT,traits>&));
    basic_istream<charT,traits>& operator>>(
        basic_ios<charT,traits>& (*pf)(basic_ios<charT,traits>&));
    basic_istream<charT,traits>& operator>>(
        ios_base& (*pf)(ios_base&));
 
    basic_istream<charT,traits>& operator>>(bool& n);
    basic_istream<charT,traits>& operator>>(short& n);
    basic_istream<charT,traits>& operator>>(unsigned short& n);
    basic_istream<charT,traits>& operator>>(int& n);
    basic_istream<charT,traits>& operator>>(unsigned int& n);
    basic_istream<charT,traits>& operator>>(long& n);
    basic_istream<charT,traits>& operator>>(unsigned long& n);
    basic_istream<charT,traits>& operator>>(long long& n);
    basic_istream<charT,traits>& operator>>(unsigned long long& n);
 
    basic_istream<charT,traits>& operator>>(float& f);
    basic_istream<charT,traits>& operator>>(double& f);
    basic_istream<charT,traits>& operator>>(long double& f);
 
    basic_istream<charT,traits>& operator>>(void*& p);
    basic_istream<charT,traits>& operator>>(
        basic_streambuf<char_type,traits>* sb);
 
    // 无格式输入：
    streamsize gcount() const;
    int_type get();
    basic_istream<charT,traits>& get(char_type& c);
    basic_istream<charT,traits>& get(char_type* s, streamsize n);
    basic_istream<charT,traits>& get(char_type* s, streamsize n,
                                     char_type delim);
    basic_istream<charT,traits>& get(basic_streambuf<char_type,traits>& sb);
    basic_istream<charT,traits>& get(basic_streambuf<char_type,traits>& sb,
                                     char_type delim);
 
    basic_istream<charT,traits>& getline(char_type* s, streamsize n);
    basic_istream<charT,traits>& getline(char_type* s, streamsize n,
                                         char_type delim);
 
 
    basic_istream<charT,traits>& ignore(
        streamsize n = 1, int_type delim = traits::eof());
    int_type                     peek();
    basic_istream<charT,traits>& read    (char_type* s, streamsize n);
    streamsize                   readsome(char_type* s, streamsize n);
 
    basic_istream<charT,traits>& putback(char_type c);
    basic_istream<charT,traits>& unget();
    int sync();
 
    pos_type tellg();
    basic_istream<charT,traits>& seekg(pos_type);
    basic_istream<charT,traits>& seekg(off_type, ios_base::seekdir);
 
protected:
    basic_istream(const basic_istream& rhs) = delete;
    basic_istream(basic_istream&& rhs);
 
    // 赋值/交换：
    basic_istream& operator=(const basic_istream& rhs) = delete;
    basic_istream& operator=(basic_istream&& rhs);
    void swap(basic_istream& rhs);
 
};

类 std::basic_iostream

template <class charT, class traits = char_traits<charT> >
class basic_iostream :
    public basic_istream<charT,traits>,
    public basic_ostream<charT,traits> {
 
public:
    // 类型
    typedef charT                     char_type;
    typedef typename traits::int_type int_type;
    typedef typename traits::pos_type pos_type;
    typedef typename traits::off_type off_type;
    typedef traits                    traits_type;
 
    // 构造函数/析构函数
    explicit basic_iostream(basic_streambuf<charT,traits>* sb);
    virtual ~basic_iostream();
 
protected:
    basic_iostream(const basic_iostream& rhs) = delete;
    basic_iostream(basic_iostream&& rhs);
 
    // 赋值/交换
    basic_iostream& operator=(const basic_iostream& rhs) = delete;
    basic_iostream& operator=(basic_iostream&& rhs);
    void swap(basic_iostream& rhs);
};