浅谈cin与cout

今天开始看了c++ ，第一章看到说cin.get()可以这样用，我猜测：那这样不就是说明cin是一个对象吗，然后调用他的iostream的类中的get函数

于是我试图找到iostream.h这个头文件，找啊找，找啊找，没找到我想要的cin这个声明对象。

于是看到#inlcude <istream.h> 

终于在这个头文件中找到了

class _CRTIMP istream : virtual public ios {

public:
    istream(streambuf*);
    virtual ~istream();

    int  ipfx(int =0);
    void isfx() { unlockbuf(); unlock(); }

    inline istream& operator>>(istream& (__cdecl * _f)(istream&));
    inline istream& operator>>(ios& (__cdecl * _f)(ios&));
    istream& operator>>(char *);
    inline istream& operator>>(unsigned char *);
    inline istream& operator>>(signed char *);
    istream& operator>>(char &);
    inline istream& operator>>(unsigned char &);
    inline istream& operator>>(signed char &);
    istream& operator>>(short &);
    istream& operator>>(unsigned short &);
    istream& operator>>(int &);
    istream& operator>>(unsigned int &);
    istream& operator>>(long &);
    istream& operator>>(unsigned long &);
    istream& operator>>(float &);
    istream& operator>>(double &);
    istream& operator>>(long double &);
    istream& operator>>(streambuf*);

    int get();

    inline istream& get(         char *,int,char ='\n');
    inline istream& get(unsigned char *,int,char ='\n');
    inline istream& get(  signed char *,int,char ='\n');

    istream& get(char &);
    inline istream& get(unsigned char &);
    inline istream& get(  signed char &);

    istream& get(streambuf&,char ='\n');
    inline istream& getline(         char *,int,char ='\n');
    inline istream& getline(unsigned char *,int,char ='\n');
    inline istream& getline(  signed char *,int,char ='\n');

    inline istream& ignore(int =1,int =EOF);
    istream& read(char *,int);
    inline istream& read(unsigned char *,int);
    inline istream& read(signed char *,int);

    int gcount() const { return x_gcount; }
    int peek();
    istream& putback(char);
    int sync();

    istream& seekg(streampos);
    istream& seekg(streamoff,ios::seek_dir);
    streampos tellg();

    void eatwhite();

再往下看，找到了cin对象的声明

extern _CRTIMP istream_withassign cin;

这个是public中的代码，也就是说

在我们调用iostream的时候，iostream中会包含istream和ostream

又因为操作运算符》重载 以及 get()等函数也在public中，并且cin对象为extern 

所以我们才可以直接输入或者输出 ，或者调用一些函数，比如 cin.get()

istream& operator>>(char *);
    inline istream& operator>>(unsigned char *);
    inline istream& operator>>(signed char *);
    istream& operator>>(char &);
    inline istream& operator>>(unsigned char &);
    inline istream& operator>>(signed char &);
    istream& operator>>(short &);
    istream& operator>>(unsigned short &);
    istream& operator>>(int &);
    istream& operator>>(unsigned int &);
    istream& operator>>(long &);
    istream& operator>>(unsigned long &);
    istream& operator>>(float &);
    istream& operator>>(double &);
    istream& operator>>(long double &);
    istream& operator>>(streambuf*);

从这里大家也看到了，为什么说cin和cout可以不管后者的变量的类型，可以直接输入或输出，而不用像scanf和printf那样繁琐

他把每种类型都包含进去了。至于什么是istream&  这些东西我不懂，我只是这样猜测的。

^_^望大神给予指导