VS 2008 C++ object array - c++

Question

So I have a class Coord which is a screen location (x, y) and a class Grid which should be an array of 13 of these Coords, read in from a text file.
The error I'm bumping against is error C2512: 'Coord' : no appropriate default constructor available grid.h 26
Although I have two constructors for the Coord.h, I thought it would use the input stream one? Kinda hacking bits and pieces from other sources here and learning at the same time so please excuse me if I'm overlooking something obvious.
Coord.h
# pragma once
// class for whole screen positions
#include "DarkGDK.h"
#include <istream>
using std::istream;
class Coord
{
float cx, cy;
public:
Coord(float x, float y) : cx(x), cy(y) {} //set components directly
Coord(istream& input); //set from input
float x()
{
return cx;
}
float y()
{
return cy;
}
Coord operator+(const Coord& c);
};
Coord::Coord(istream& input)
{
input >> cx >> cy;
}
Coord Coord::operator+(const Coord& c)
{
return Coord(cx+c.cx, cy+c.cy);
}
Grid.h
# pragma once
// class for the grid array
#include "DarkGDK.h"
#include "Coord.h"
#include <fstream>
#include <iostream>
using namespace std;
const int N = 13;
const char filename[] = "grid.txt";
class Grid
{
Coord gridpos[N];
public:
Grid();
void FillGrid(); //read-in coord values
};
Grid::Grid()
{
FillGrid();
}
void Grid::FillGrid()
{
int i;
ifstream filein(filename, ios::in); //file for reading
for(i=0; !filein.eof(); i++)
{
filein >> gridpos[i].x >> gridpos[i].y; //read in
filein.close();
}
}
Any help is appreciated, thanks.

Answer 1

There are numerous little errors in your code. Here's a version that works with some annotations.
#include <fstream>
#include <iostream>
using namespace std;
const int N = 13;
const char filename[] = "grid.txt";
class Coord
{
float cx, cy;
public:
// Default constructor required to declare array: eg Coord c[23];
Coord() : cx(0), cy(0)
{}
Coord(float x, float y) : cx(x), cy(y)
{}
// You were returning float instead of float& which means you could not update
float& x()
{
return cx;
}
float& y()
{
return cy;
}
Coord Coord::operator+(const Coord& c)
{
return Coord(cx+c.cx, cy+c.cy);
}
friend istream& operator>>(istream& input, Coord& rhs)
{
input >> rhs.cx >> rhs.cy;
return input;
}
};
class Grid
{
Coord gridpos[N];
public:
Grid()
{
FillGrid();
}
void FillGrid()
{
int i;
ifstream filein(filename, ios::in); //file for reading
for(i=0; !filein.eof(); i++)
{
filein >> gridpos[i];
}
// Close the file after you have finished reading from it
filein.close();
}
};
int main()
{
Grid g;
return 0;
}