Core Dump when testing mini Matrix ADT - c++

Question

I am currently working on a project implementing a templated matrix class; however, whenever I try to run my test function, the program crashes and core dumps. The following is the output I get:
0 0
[3 3 1 2 3 4 5 6 9 8 10]
[1 2 3
4 5 6
9 8 10]
stream out sucessInvalid Input for matrix
stream in sucessError: matrix Multiplication not defined.
[1 2 3
4 5 6
9 8 10]
Error: The addition of two matrices of different demensions is not defined.
Error: The addition of two matrices of different demensions is not defined.
7700640
7700576
Error: The addition of two matrices of different demensions is not defined.
*** glibc detected *** ./a.out: free(): invalid pointer: 0x00000030143b0778 ***
======= Backtrace: ========= <Continues> ...
The Calling function is:
TestingMatrix(){
matrix<int> a, b, c;
//Three empty matrices are created
cout << a.numrows() << " " << a.numcols() << endl; // yields 0 0
cin >> a; // User types [3 3 1 2 3 6 5 4 9 8 10]
// This will create a 3 by 3 matrix
cout << a;
cin >> b; //User types [3 2 9 1 2 3 4 5]
cout << b;
c=a*b;
cout << c << endl;
cout << b+c << endl;
matrix<int> d(5*b); // d is initialized to 5*b
cout << d << endl;
cout << a[0][0] << endl;
//Should printout 1
cout << a[1][2] << endl;
//Should printout 4
d = a + b;
//This should cause an exception that you
//are able to handle; The sizes of a and b don’t agree.
}//End of TestingMatrix() function
The matrix class is as follows:
// matrix.h
#ifndef matrix_H
#define matrix_H
#include <iostream>
#include <cstdlib>
using namespace std;
template <class mType> class matrix {
public:
matrix() : N(0), M(0), origin(NULL) { /* EMPTY */ }
matrix(int n, int m): N(n), M(m), origin(NULL) {
allocate(n,m);
}
~matrix() {
clear();
}
matrix & operator=(const matrix &rhs) {
if (this != &rhs) { //Check to see they're not the same instance
this->clear();
this->allocate(rhs.numrows(), rhs.numcols());
for(int i=0; i<N; ++i)
for (int j=0; j<M; ++j)
this->origin[i][j] = rhs[i][j];
}
return *this;
}
matrix & operator+=(const matrix &rhs) {
try {
if ( this->numrows() != rhs.numrows() ||
this->numcols() != rhs.numcols() )
throw 1;
}
catch (int e)
{
cerr << "Error: The addition of two matrices of different demensions is not defined." << endl;
return *this;
}
for(int i=0; i<N; ++i)
for (int j=0; j<M; ++j)
this->origin[i][j] += rhs[i][j];
return *this;
}
const matrix operator+(const matrix &rhs) const {
matrix tmp = *this; // tmp copy so we can use the += operator
return (tmp += rhs); // return answer
}
const matrix operator*(const matrix &rhs) const {
try {
if ( this->numcols() != rhs.numrows() )
throw 1;
}
catch (int e)
{
cerr << "Error: matrix Multiplication not defined." << endl;
return *this;
}
matrix<mType> returnmatrix(this->numrows(), rhs.numcols());
for (int i=0; i<returnmatrix.numrows(); ++i)
for (int j=0; j<returnmatrix.numcols(); ++j)
for (int k=0; k < this->numcols(); ++k)
returnmatrix[i][j] += *this[i][k] * rhs[k][j];
return returnmatrix;
}
inline int const numrows() const {
return N;
}
inline int const numcols() const {
return M;
}
void allocate(int n, int m) {
if (origin)
clear();
origin = new mType* [n];
for (int i=0; i<n; ++i)
origin[i] = new mType[m];
M=m;
N=n;
}
void clear() {
if (origin) {
for(int i = 0; i < N; i++)
delete[] origin[i];
delete origin;
}
M=N=0; // Reset
origin=NULL;
}
mType* operator [] (const int index) { return origin[index]; }
const mType* operator [] (const int index) const { return origin[index]; }
friend matrix<mType> operator*( mType factor, const matrix<mType> rhs ) {
matrix<mType> out(rhs.numrows() , rhs.numcols());
for (int i=0; i<rhs.numrows(); ++i) {
for (int j=0; j<rhs.numcols(); ++j) {
out[i][j] = rhs[i][j]*factor;
}
}
return out;
}
friend ostream& operator<< (ostream& out, const matrix<mType>& A) {
if (A.numrows() > 0 && 0 < A.numcols()) {
out <<"[";
for (int j=0; j<A.numcols(); ++j) {
out << A[0][j] << " ";
}
for (int i=1; i<A.numrows(); ++i) {
out << endl;
for (int j=0; j<A.numcols(); ++j) {
out << " " << A[i][j];
}
}
out << "]" <<endl;
}
return out;
}
friend istream& operator>> (istream& in, matrix<mType> &A) {
//[3 2 9 1 2 3 4 5]
//toss first char
try {
if (in.get() != '[')
throw 1;
int N, M;
mType tmp;
in >> N;
in >> M;
A = matrix<mType>(N,M);
for (int i=0; i<N; ++i)
for (int j = 0; j < M; j++)
{
in >> tmp;
A[i][j] = tmp;
}
in.get();
}
catch (int e) {
cerr << "Invalid Input for matrix" << endl;
}
return in;
}
private:
int N, M;
mType ** origin;
};
#endif
Does anyone have any idea as to how resolve this? I'm pretty lost as to the source fo this issue.
Thanks in advance.

Answer 1

Since you have dynamically allocated resources, you should follow the rule of three and implement a copy constructor. Currently a copy construction will use the compiler generated copy constructor, making a copy of the pointer to the underlying data, without copying the data itself.
There is at least one copy construction in your addition operator:
const matrix operator+(const matrix &rhs) const {
matrix tmp = *this; // copy!
return (tmp += rhs); // potentially another copy
}

Answer 2

You have no copy c-tor and compiler will generate default, which does memberwise-copy, but if you have dynamically allocated resources in class - you should have your own copy c-tor, that do deep-copy.