overload

[dark777]

I know that this community is not from c ++, but for some time I 
studied how to do overload of ostream operators in c ++ and I 
even managed to get to this result, I got to this result in 
another post done here but I did not understand the that it 
returns this error below:


bin2.cxx:44:43: error: expected ‘,’ or ‘...’ before ‘(’ token
    std::ostream& operator<<(std::ios_base& (__cdecl 
*_Pfn)(std::ios_base&))
                                            ^
bin2.cxx: In member function ‘std::ostream& 
BinStream::operator<<(std::ios_base&)’:
bin2.cxx:46:16: error: ‘_Pfn’ was not declared in this scope
     return os <<_Pfn;

so that the output is the same as below:

         127 em binario:     0001111111
         127 em octal:       177
         127 em binario:     0001111111
         127 em hexadecimal: 7f
         127 em decimal:     127
         127 em binario:     0001111111

and not this:

         127 em binario:     0001111111
         127 em octal:       0001111111
         127 em binario:     0001111111
         127 em hexadecimal: 0001111111
         127 em decimal:     0001111111
         127 em binario:     0001111111


#include <ios> //ios_base
#include <sstream>
#include <climits>   // CHAR_BIT
#include <iostream>
#include <algorithm> // reverse

     struct BinStream
    {
          std::ostream& os;
          BinStream(std::ostream& os) : os(os) {}

      std::string binario(unsigned int n)
      {
       //converte numero para string de bits
       std::stringstream bitsInReverse;
       //int nBits = sizeof(n) * CHAR_BIT;
       unsigned int nBits = sizeof(n)*2.5;

       while (nBits-- > 0)
       {
        bitsInReverse << (n & 1);
        n >>= 1;
       }

       std::string bits(bitsInReverse.str());
       std::reverse(bits.begin(), bits.end());
       return bits;
      }

          template<class T>
          BinStream& operator<<(T&& value)
          {
              os << value;
              return *this;
          }

          BinStream& operator<<(int value)
          {
              os << binario(value);
              return *this;
          }

          std::ostream& operator<<(std::ios_base& (__cdecl 
*_Pfn)(std::ios_base&))
          {
              return os << _Pfn;
          }
      };

      struct Bin
      {
          friend BinStream operator<<(std::ostream& os, const Bin& 
f);
      } bin;

      BinStream operator<<(std::ostream& os, const Bin& f)
      {
          return BinStream(os);
      }

  int main()
  {
   std::cout << "\n\t127 em binario:     " << binario(127)
             << "\n\t127 em binario:     " << bin << 127
             << "\n\t127 em octal:       " << std::oct << 127
             << "\n\t127 em binario:     " << bin << 127
             << "\n\t127 em hexadecimal: " << std::hex << 127
             << "\n\t127 em binario:     " << bin << 127
             << "\n\t127 em decimal:     " << std::dec << 127
             << "\n\t127 em binario:     " << bin << 127 << "\n\n";
  }