C++ 重载操作符 ＜＜实现模拟输出语句： cout ＜＜ endl；

#include <iostream>
#define Stream std::basic_ostream<T1, T2>&
template<typename T1, typename T2>
Stream CRLF(Stream _out)
{
  putchar('\n');
  return _out.flush(); //清缓冲区 
}
int main(void)
{
  std::cout << "第一行" << CRLF;  //已脱离std::空间 
  CRLF(std::cout);  //还可以这样调用，单独输出一空行 
  std::cout << "第三行" << CRLF;
  //std::cout << "第四行" << endl; //必须用std::endl 
  return 0;
}
/*
第一行
        //第二行是空行
第三行
--------------------------------
Process exited after 1.197 seconds with return value 0
请按任意键继续. . .
*/

#include <iostream>
std::ostream& endl (std::ostream& _os)
{
  _os.put('\n');
  _os.flush();
  return _os;
}
int main(void)
{
  std::cout << 1 << endl <<endl;  //这是自定义的 endl 
  std::cout << 2 << std::endl;  //这是std的 endl 
  endl(std::cout);      //这是自定义的 endl 
  std::cout << "========" << endl;
  std::endl(std::cout);   //这是std的 endl 
  std::cout << "========" << std::endl;
  return 0;
}
/*
1
2
========
========
--------------------------------
Process exited after 0.9518 seconds with return value 0
请按任意键继续. . .
*/

#include <iostream>
#include <string>
#include <typeinfo>
#define endl "\n"
class myOutText{
public:
    myOutText &operator << (auto s) {
    std::string str;
    if (typeid(s).name()==typeid(std::string("")).name()) str=s;
    if (str==endl) { 
      std::cout << endl;
      std::cout.flush();
    }
    else
      std::cout << s ;
    //return *this; //返回自身引用以支持连续操作
    }
};
int main(void)
{
    myOutText cout; 
  auto a = "abc";
  double b = 8.9;
  cout << "string1-" << a;
    cout << endl;
    cout << "1<<23<<4.56:" << endl;
    cout << 1 << 23 << 4.56e-7 << " "
     << b << endl << "crlf" << endl;
  std::string str = "endl";
    cout << str << endl << endl;
    return 0;
}
/*
string1-abc
1<<23<<4.56:
1234.56e-007 8.9
crlf
endl
--------------------------------
Process exited after 1.198 seconds with return value 0
请按任意键继续. . .
*/

#include <iostream>
class myOutText{
public:
    myOutText &operator << (auto s) {
        std::cout << s;
      return *this;
    }
    myOutText &operator << (void(*obj)(myOutText&)) {
      obj(*this);
        return *this;
    }
    void flush() {
        std::cout.flush();
    }
};
void endl(myOutText &obj) 
{
    obj << '\n';
    obj.flush();
}
int main(void)
{
    myOutText cout; 
  std::string str="abcd";
    cout << "string<<" << str << endl;
    cout << "1<<2<<" << endl <<endl;
    cout << 1 << 2.3 << str << endl; 
    return 0;
}
/*
string<<abcd
1<<2<<
12.3abcd
--------------------------------
Process exited after 0.4635 seconds with return value 0
请按任意键继续. . .
*/