<iostream>头文件源码

下面是iostream头文件的源码：

#ifndef _IOSTREAM_H
#define _IOSTREAM_H

#include <ios>      // basic_ios, streampos, streamoff, etc.
#include <streambuf>    // basic_streambuf
#include <istream>  // basic_istream
#include <ostream>  // basic_ostream
#include <cstdio>   // EOF, FILE
#include <wchar.h>  // wchar_t

namespace std {
    extern istream cin;    // standard input stream
    extern ostream cout;   // standard output stream
    extern ostream cerr;   // standard error (output) stream
    extern ostream clog;   // standard logging (output) stream

    template <class charT, class traits = char_traits<charT>>
    class basic_iostream : public basic_ios<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;

        // constructors
        explicit basic_iostream(basic_streambuf<charT, traits>* sb);
        virtual ~basic_iostream();

        // delete copy and move constructors and assignments
        basic_iostream(const basic_iostream&) = delete;
        basic_iostream& operator=(const basic_iostream&) = delete;
        basic_iostream(basic_iostream&&) = delete;
        basic_iostream& operator=(basic_iostream&&) = delete;

        // basic_iostream operations
        basic_ios<charT, traits>* tie() const;
        basic_ios<charT, traits>* tie(basic_ios<charT, traits>* tiestr);
        basic_streambuf<charT, traits>* rdbuf() const;
        void rdbuf(basic_streambuf<charT, traits>* sb);

        // conversions
        operator void*() const;
        bool operator!() const;

        // unformatted input
        int_type get();
        basic_iostream<charT, traits>& get(char_type& c);
        basic_iostream<charT, traits>& get(char_type* s, streamsize n);
        basic_iostream<charT, traits>& get(char_type* s, streamsize n, char_type delim);
        basic_iostream<charT, traits>& getline(char_type* s, streamsize n);
        basic_iostream<charT, traits>& getline(char_type* s, streamsize n, char_type delim);
        basic_iostream<charT, traits>& ignore(streamsize n = 1, int_type delim = traits::eof());
        basic_iostream<charT, traits>& read(char_type* s, streamsize n);
        streamsize readsome(char_type* s, streamsize n);

        // unformatted output
        basic_iostream<charT, traits>& put(char_type c);
        basic_iostream<charT, traits>& write(const char_type* s, streamsize n);

        // formatted input
        basic_iostream<charT, traits>& operator>>(basic_ios<charT, traits>& (*pf)(basic_ios<charT, traits>&));
        basic_iostream<charT, traits>& operator>>(basic_istream<charT, traits>& (*pf)(basic_istream<charT, traits>&));
        basic_iostream<charT, traits>& operator>>(basic_streambuf<charT, traits>* sb);

        basic_iostream<charT, traits>& operator>>(bool& n);
        basic_iostream<charT, traits>& operator>>(short& n);
        basic_iostream<charT, traits>& operator>>(unsigned short& n);
        basic_iostream<charT, traits>& operator>>(int& n);
        basic_iostream<charT, traits>& operator>>(unsigned int& n);
        basic_iostream<charT, traits>& operator>>(long& n);
        basic_iostream<charT, traits>& operator>>(unsigned long& n);
        basic_iostream<charT, traits>& operator>>(long long& n);
        basic_iostream<charT, traits>& operator>>(unsigned long long& n);
        basic_iostream<charT, traits>& operator>>(float& f);
        basic_iostream<charT, traits>& operator>>(double& f);
        basic_iostream<charT, traits>& operator>>(long double& f);
        basic_iostream<charT, traits>& operator>>(void*& p);

        basic_iostream<charT, traits>& operator>>(basic_ios<charT, traits>& (*pf)(basic_ios<charT, traits>&));
        basic_iostream<charT, traits>& operator>>(basic_istream<charT, traits>& (*pf)(basic_istream<charT, traits>&));
        basic_iostream<charT, traits>& operator>>(basic_streambuf<charT, traits>* sb);

        // formatted output
        basic_iostream<charT, traits>& operator<<(basic_ios<charT, traits>& (*pf)(basic_ios<charT, traits>&));
        basic_iostream<charT, traits>& operator<<(basic_ostream<charT, traits>& (*pf)(basic_ostream<charT, traits>&));
        basic_iostream<charT, traits>& operator<<(basic_streambuf<charT, traits>* sb);

        basic_iostream<charT, traits>& operator<<(bool n);
        basic_iostream<charT, traits>& operator<<(short n);
        basic_iostream<charT, traits>& operator<<(unsigned short n);
        basic_iostream<charT, traits>& operator<<(int n);
        basic_iostream<charT, traits>& operator<<(unsigned int n);
        basic_iostream<charT, traits>& operator<<(long n);
        basic_iostream<charT, traits>& operator<<(unsigned long n);
        basic_iostream<charT, traits>& operator<<(long long n);
        basic_iostream<charT, traits>& operator<<(unsigned long long n);
        basic_iostream<charT, traits>& operator<<(float f);
        basic_iostream<charT, traits>& operator<<(double f);
        basic_iostream<charT, traits>& operator<<(long double f);
        basic_iostream<charT, traits>& operator<<(const void* p);
        basic_iostream<charT, traits>& operator<<(basic_ios<charT, traits>& (*pf)(basic_ios<charT, traits>&));
        basic_iostream<charT, traits>& operator<<(basic_ostream<charT, traits>& (*pf)(basic_ostream<charT, traits>&));
        basic_iostream<charT, traits>& operator<<(basic_streambuf<charT, traits>* sb);
    };

    // typedefs
    using iostream = basic_iostream<char>;
    using wiostream = basic_iostream<wchar_t>;

    // manipulators
    extern basic_istream<char>& ws(basic_istream<char>& is);
    extern basic_istream<wchar_t>& ws(basic_istream<wchar_t>& is);

    // object instances
    extern istream cin;
    extern ostream cout;
    extern ostream cerr;
    extern ostream clog;

    // non-member functions
    template <class charT, class traits>
    basic_istream<charT, traits>& flush(basic_istream<charT, traits>& is);
    template <class charT, class traits>
    basic_ostream<charT, traits>& flush(basic_ostream<charT, traits>& os);

    template <class charT, class traits>
    basic_istream<charT, traits>& ws(basic_istream<charT, traits>& is);

    template <class charT, class traits>
    void swap(basic_ios<charT, traits>& a, basic_ios<charT, traits>& b) noexcept;
}

#endif /* _IOSTREAM_H */

该头文件定义了C++标准输入输出流（cin、cout、cerr、clog）以及基本的输入输出流对象。同时还定义了一系列输入输出的操作符和控制符。