Re: Overloaded << Operator Error ?? why

From:
Rolf Magnus <ramagnus@t-online.de>
Newsgroups:
comp.lang.c++
Date:
Thu, 10 Apr 2008 19:39:51 +0200
Message-ID:
<ftljd7$a0n$02$1@news.t-online.com>
pallavsingh81@gmail.com wrote:

#include<iostream.h>


This is an obsolete non-standard header. You shouldn't use it.

//prefix and postfix Operator overloading // Inorder to see effect
overload operator <<

class A
{
  public :
  int i,j;
  A(int _i,int _j):i(_i),j(_j){}
  A & operator++();
  const A operator++(int);

};

A& A::operator++()
{
  this->i = this->i + 1;
  this->j = this->j +1 ;
  return *this;
}

const A A::operator++(int)
{
 A obj = *this;
 this->i = this->i + 1;
 this->j = this->j +1 ;

 return obj;
}

ostream & operator << (ostream & out , A & obj)


So this operator claims to modify A. Since it doesn't, the second parameter
should be a reference to const A. This will also solve your problem.

{
   out<<"Value of i "<<obj.i<<endl;
   out<<"Value of j "<<obj.j<<endl;
   return out;
}

int main()
{

A obj(10,20);
cout<<++obj;
cout<<obj++; // Error Why ????????????????


Because the object returned by the operator is a temporary, which cannot be
bound to a non-const reference.

return 0;
}

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