CODEWITHSUNDEEP
c++
googg
googg

Reputation: 13

Specific case for 'no match for ‘operator<<’'

I am facing a problem whereby I have already done my operator << but it doesn't work for some reason. I tried countless ways and the one below made the most sense to me. But still failed. Can anyone show me the proper way to overload (*this)[index] in this specific instance(Refer to class VisiblePolygon)? Class Polygon will consist of the operator << to the class VisiblePolygon. Can't find a solution for this specific case. Hence I'm here. Thanks!

Compile error:

In function ‘std::ostream& operator<<(std::ostream&, const Polygon&)’:

polygon.h:103:8: error: no match for ‘operator<<’ (operand types are ‘std::ostream {aka std::basic_ostream<char>}’ and ‘Object::PointType’)

     os <<p.mpt[i];
     ~~~^~~~~~~~~~

My code:

#include <iostream>
#include <algorithm>
#include <functional>
#include <list>
#include <cmath>


class Polygon : public Point 
{
  private:
    Object::PointType *mpt; //An array of points
    int msize; 

  public:
    PointType& operator[](int index)  const
    {
      return mpt[index];
    }

    Polygon(const PointType* points, int npoints); 

    Polygon(PointType* points, int npoints, float depth) //constructor
      : Point(*points,depth),
      mpt{new Object::PointType[npoints]},
      msize(npoints)
    {
       for(int i = 0; i < msize; ++i)
       {
         mpt[i]  = points[i];
       }
    }

    Polygon center() 
    {
      //..
    }

    float x()
    {   
      //...
    }

    float y()
    {
      //...
    }

    int size() const
    {
      return msize;
    }

    virtual void render() const 
    {}

    friend std::ostream& operator<<(std::ostream& os, const Polygon& p)
    {   
      for (int i = 0; i < p.msize; ++i)
      {
        os <<p.mpt[i]; 
        return os;              
      }
    }
};

class VisiblePolygon : public Polygon
{
  public:
    VisiblePolygon(const Object::PointType* points, int size) :
      Polygon(points, size)
    {
    }

    void render() const override
    {
        std::cout << "Polygon with vertices: ";
        for (int index = 0; index < size(); ++index)
        {
            std::cout << (*this)[index] << " ";
        }
        std::cout << std::endl;
    }
};

Upvotes: 1

Views: 61

Answers (1)

rustyx
rustyx

Reputation: 85266

The error

In function ‘std::ostream& operator<<(std::ostream&, const Polygon&)’: polygon.h:103:8: error: no match for ‘operator<<’ (operand types are ‘std::ostream {aka std::basic_ostream}’ and ‘Object::PointType’)

basically says "OK you have operator << for Polygon, now you need one for PointType as well".

Unrelated, but return os; should probably be outside the loop.

Upvotes: 2

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