#include<iostream>
#include<stdexcept>
#include<cstring>
using namespace std;

template<typename T>
class matrix {
public:
	int width, height;
	T* data;

//	matrix() : width(0), height(0), data(0) {}

	matrix(int w, int h) : width(w), height(h) {
		data = new T[w*h];
		zero();
	}

	void zero(){
		for(int i = 0; i < width*height; i++)
			data[i] = 0.0;
	}

	matrix(const matrix<T>& other) {
		width = other.width;
		height = other.height;
		data = new T[width*height];
		// Assumes T is a basic type that doesn't require a constructor call
		memcpy(data, o.data, sizeof(T) * width * height);
	}

	T& at(int x, int y){
		return data[x + y * width];
	}

	matrix<T>& operator=(matrix& o) {
		// If the height or width don't match, we'll adapt to the other matrix
		if(o.height != height || o.width != width){
			height = o.height;
			width = o.width;
			delete [] data;
			data = new T[height*width];
		}
		// Again, assumes 
		memcpy(data, o.data, sizeof(T) * width * height);
		return *this;
	}

	matrix<T> operator+(matrix& o) {
		if(o.height != height || o.width != width)
			throw runtime_error("Matrix size didn't match");
		matrix<T> result(width, height);	
		for(int i = 0; i < height; i++) {
			for(int j = 0; j < width; j++)
				result.at(i, j) = at(i, j) + o.at(i, j);
		}
		return result;
	}

	~matrix(){
		delete [] data;
	}
};

template<typename T>
ostream& operator<<(ostream& out, matrix<T>& m){
	for(int i = 0; i < m.height; i++) {
		for(int j = 0; j < m.width; j++)
			out << m.at(i, j) << "\t";
		out << endl;
	}
	return out;
}

int main(){
	matrix<double> dblm(4, 4);
	dblm.at(1, 1) = 234.56;
	cout << dblm << endl;
	matrix<double> extra(4, 4);
	extra.at(1, 1) = 2.345;
	matrix<double> result(dblm + extra);
	cout << result;

	matrix<double> copy(4, 4);
	copy = result; // Uses operator =

	matrix<double> other_copy(result); // Uses copy constructor


	return 0;
}