for some reason, I seem to be having an exception whenever I call the following (assume A,B & C are all matrices, and that no matrix multiplication rules are broken):
c=a*b;
I have been stepping through my code for hours now, and cannot for the life of me find whats wrong.
any takers? I think it might be an issue with either the allocate() or clear() functions, or the copy constructor/assignment operator.
Thanks in advance!
// 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(const matrix<mType> &m) {
if (origin)
clear();
origin = new mType* [m.numrows()];
for (int i=0; i<m.numrows(); ++i)
origin[i] = new mType[m.numcols()];
}
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
}
friend const matrix operator*(const matrix &that, const matrix &rhs) {
try {
if ( that.numcols() != rhs.numrows() )
throw 1;
}
catch (int e)
{
cerr << "Error: matrix Multiplication not defined." << endl;
return that;
}
matrix<mType> returnmatrix(that.numrows(), rhs.numcols());
int x=0;
for (int i=0; i<returnmatrix.numrows(); ++i)
for (int j=0; j<returnmatrix.numcols(); ++j)
for (int k=0; k < that.numcols(); ++k){
cout << (++x)<<endl;
returnmatrix[i][j] += that[i][k] * rhs[k][j];}
cout << "rt" <<endl;
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 (this->origin) {
for(int i = 0; i < N; i++)
delete[] origin[i];
delete this->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();
in.ignore();
}
catch (int e) {
cerr << "Invalid Input for matrix" << endl;
}
return in;
}
private:
int N, M;
mType ** origin;
};
#endif
REVISED:
// 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(const matrix<mType> &m) {
origin = new mType* [m.numrows()];
for (int i=0; i<m.numrows(); ++i)
origin[i] = new mType[m.numcols()];
for (int i=0; i<N;++i)
for (int j = 0; j < M; j++)
{
origin[i][j] = m[i][j];
}
}
matrix(int n, int m): N(n), M(m), origin(NULL) {
allocate(n,m);
for (int i=0; i<N;++i)
for (int j = 0; j < M; j++)
{
origin[i][j] = 0;
}
}
~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
}
friend const matrix operator*(const matrix &that, const matrix &rhs) {
try {
if ( that.numcols() != rhs.numrows() )
throw 1;
}
catch (int e)
{
cerr << "Error: matrix Multiplication not defined." << endl;
return that;
}
matrix<mType> returnmatrix(that.numrows(), rhs.numcols());
int x=0;
for (int i=0; i<returnmatrix.numrows(); ++i)
for (int j=0; j<returnmatrix.numcols(); ++j)
for (int k=0; k < that.numcols(); ++k){
cout << (++x)<<endl;
returnmatrix[i][j] += that[i][k] * rhs[k][j];}
cout << "rt" <<endl;
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 (this->origin) {
for(int i = 0; i < N; i++)
delete[] origin[i];
delete this->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();
in.ignore();
}
catch (int e) {
cerr << "Invalid Input for matrix" << endl;
}
return in;
}
private:
int N, M;
mType ** origin;
};
#endif
Quite a lot of code but I just looked at the copy constructor and it has two serious mistakes in it.
First mistake
origin is uninitialized at this point, so you cannot test it’s value. Just remove these two lines. Remember a constructor initializes a new object, it’s wrong if a constructor is testing the object for what is already there.
Second mistake
Your copy constructor doesn’t copy anything! It creates a matrix of the right size but it doesn’t copy the matrix values!
I would guess the first error is the cause of your crash, the second error will just mean you get garbage results.