Question

I am getting the following errors when making Arrays of two obecjts.. Edge and Box.

error: conversion from 'const Edge*' to non-scalar type 'Edge' requested.

I am hoping to return an array of Edges.

On this header file:

class Box
{
private:
    bool playerOwned; 
    bool computerOwned;
    Edge boxEdges[4];
    int openEdges;
    bool full;

public:
    Box();
    Box(int x, int y);
    void setEdges(Edge boxTop, Edge boxBottom, Edge boxLeft, Edge boxRight);
    void addEdgeToBox(Edge edge); //add edge to edgeArray.
    void setPlayerOwned(bool point);
    Edge getBoxEdges() const {return boxEdges;}                ****//Error****
    bool getPlayerOwned() const {return playerOwned;}
    void setComputerOwned(bool point);
    bool getComputerOwned()const {return computerOwned;}
    int getOpenEdges() const {return openEdges;}
    bool isFull()const {return full;}

};
std::ostream& operator<< (std::ostream& out, Box box);

I get the same error except replace ‘Edge’ with ‘Box’ on the following line in a non-header file attempting to create a Box.

  Box box = new Box(x+i,y);

Answer 1

Box box = new Box(x+i,y);  //error

One error is right here. You should write this as:

Box *box = new Box(x+i,y); //ok

It is because when you use new, you’re allocating memory, and only a pointer can hold a memory, so box has to be pointer type.

Similarly,

Edge getBoxEdges() const {return boxEdges;}  //error

should be written as:

const Edge* getBoxEdges() const {return boxEdges;}  //ok

It is because boxEdges is an array, which can decay into pointer type to its first element, and since it is const member function, boxEdges will decay into const Edge*.

---

By the way, instead of pointer in the first case, you use automatic object as:

Box box(x+i, y); //ok

---

I would suggest you to make the second parameter of operator<< a const reference:

//std::ostream& operator<< (std::ostream& out, Box box); //don't use this
std::ostream& operator<< (std::ostream& out, Box const & box); //use this

This avoids unnecessary copy!