Displaying Points

[megascruples]

Im still a bit new to pointers and structs, and i dont understand why my display points function isnt working. Im thinking what im returning in readPoints isnt working right but it doesnt make much sense for the display to not work at all. Any suggestions would be greatly appriciated.

here is read points

Points* readPoints(const char* file_name)
{
	ifstream input_file;
	input_file.open(file_name);
	
	int num_points;
	input_file >> num_points;
	
	Point** point_array = new Point*[num_points];
	
	for(int i = 0; i < num_points; i++)
	{
		double x;
		input_file >> x;
		double y;
		input_file >> y;
		double z;
		input_file >> z;
		
		Point* point = createPoint(x, y, z);
		point_array[i] = point;
	}
	
    Points* points = new Points;
    points->points = point_array;
	input_file.close();
	
	return points;
}

and display ponts

void displayPoints(const Points* points)
{
	Point** points_array = points->points;
	int num_points = points->num_points;
	
	for(int i = 0; i < num_points; i++)
	{
		Point* point = points_array[i];
		cout<< point <<endl;
		displayPoint(point);
	}
}

and here are the other functions that i use

Point* createPoint(double x, double y, double z)
{
	Point* point = new Point;
	point->x = x;
	point->y = y;
	point->z = z;
	
	return point;
}

void displayPoint(const Point* const point)
{
	cout << setprecision(3) <<fixed;
	cout<< "(" << point->x << ", " << point->y << ", " << point->z << ")" <<endl;
}

[MiiNiPaa]

Aside from unneeded indirection in many places, you do not assigning anything to points->num_points in readPoints function.

[megascruples]

Thank you! its displaying it now. Would you have any idea of how to sort points from a reference number?

[MiiNiPaa]

how to sort points from a reference number?

I am not sure I understand you.

How points should be ordered?

[megascruples]

I have to sort points (x, y, z) from the distance of the reference point

[MiiNiPaa]

Either use handcrafted sorting function or use library provided instruments: http://ideone.com/04EpZ4

Adapt to your case.

[megascruples]

I know i need to make my own sorting function, i just dont understand how to sort points from a reference point. Would i need to determine the distance from refpoint with all the points then determine which distance is greater?

[MiiNiPaa]

You will need a comparsion function which will return if first point is closer to reference point than second one. Then you can just pass comparsion function to std::sort alghorithm

You can make comparsion function in two ways:
1) if ref point is known at compile time, you can just hardcode it to your function.
2) Otherwise you should pass it as a parameter to your function and then bind real reference point to your function (as I done in my example).
3) Use lambdas.