I am attempting to create an overloaded operator for a matrix class that I have built. My matrix class stores the matrix in a dynamically allocated multidimensional array. I am simply trying to test my overloaded operator by multiplying two matrices together that are exactly the same and display the output. I am getting weird results and I believe it has to do with one of the conditionals on my for loops. I have however walked through all of my for loops and can find nothing wrong. The matrices I am multiplying together are both 6x6.
My overloaded operator
template <typename T>
const matrix<T> matrix<T>::operator * (const matrix& right) const
{
matrix<T> c = right;
int sum_elems;
for( int i = 0; i < this->rows - 1; ++i)
{
for(int j = 0; j < right.cols - 1; ++j)
{
sum_elems = 0;
for( int k = 0; k < right.rows - 1; ++k)
{
sum_elems += this->the_matrix[i][k] * right.the_matrix[k][j];
}
c.the_matrix[i][j] = sum_elems;
}
}
return c;
}
Now my call to the overloaded operator in my main function:
std::cout << my_matrix;
matrix<int> copy_matrix;
copy_matrix = my_matrix * my_matrix;
std::cout << copy_matrix;
My output:
The Matrix:
0 1 0 1 1 0
1 0 1 0 1 1
0 1 0 1 0 1
1 0 1 0 1 0
1 1 0 1 0 1
0 1 1 0 1 0
The Matrix:
-1 33 139587680 18 38 75
139587680 18 38 75 157 1
139587712 38 1470 4365 10411 1
139587744 75 4365 19058932 64514866 0
139587776 157 10411 64514866 1136204102 1
139596144 1 1 0 1 0
As you can see it seems that I am stepping out of bounds on one of my arrays. I can not seem to find where though. I appreciate your help in advance.
Edit: As requested my full implementation of my matrix class
Matrix Definitions:
template <typename T>
class matrix
{
public:
//Default Constructor
matrix();
//Overloaded Constructor
matrix(std::ifstream&, const char*);
//Copy Constructor
matrix(const matrix&);
//Destructor
~matrix();
//overloaded operators
T* operator [] (T);
const matrix operator * (const matrix&) const;
matrix& operator = (const matrix&);
friend std::ostream& operator << <T> (std::ostream&, const matrix<T>&);
private:
T** the_matrix;
unsigned rows, cols;
Matrix Implementation:
/* Template version of matrix class */
/*---------------------------------------------------------------------------*/
// Default contructor
template <typename T>
matrix<T>::matrix() { }
// Overloaded contructor
template <typename T>
matrix<T>::matrix( std::ifstream& in, const char* file)
{
// declare the variables to be used
T vertices, edges, u, v;
std::string line;
// open file for reading
in.open(file);
// get number of vertices
in >> vertices;
// throw away second line
std::getline(in, line);
std::getline(in, line);
// get number of edges and dump them in two arrays
in >> edges;
T edge1 [edges];
T edge2 [edges];
int j = 0, k = 0;
for(int a = 0; a < edges; ++a)
{
in >> u >> v;
edge1[j] = u;
edge2[k] = v;
++j;
++k;
}
in.close();
// Create multi-dim-dynamic array
rows = vertices;
cols = vertices;
the_matrix = new T*[rows];
for( int b = 0; b < rows; ++b)
{
the_matrix[b] = new T [rows];
}
// Initialize array values to zero
for ( int c = 0; c < rows; ++c)
{
for( int d = 0; d < cols; ++d)
{
the_matrix[c][d] = 0;
}
}
// push the edges to the matrix
for( int e = 0; e < edges; ++e)
{
the_matrix[edge1[e] - 1][edge2[e] - 1] = 1;
}
for ( int f = 0; f < edges; ++f)
{
the_matrix[edge2[f] - 1][edge1[f]-1] = 1;
}
}
// Copy Constructor
template <typename T>
matrix<T>::matrix(const matrix& left)
{
the_matrix = left.the_matrix;
rows = left.rows;
cols = left.cols;
spath = left.spath;
}
// Destructor
template <typename T>
matrix<T>::~matrix()
{
// Deletes the data in reverse order of allocation
for( int a = cols; a > 0; --a)
{
delete[ ] the_matrix[a];
}
delete[ ] the_matrix;
}
// Overloaded * Operator
template <typename T>
const matrix<T> matrix<T>::operator * (const matrix& right) const
{
matrix<T> c = right;
T sum_elems;
for( int i = 0; i < this->rows - 1; ++i)
{
for(int j = 0; j < right.cols - 1; ++j)
{
sum_elems = 0;
for( int k = 0; k < right.rows - 1; ++k)
{
sum_elems += this->the_matrix[i][k] * right.the_matrix[k][j];
}
c.the_matrix[i][j] = sum_elems;
}
}
return c;
}
// Overloaded assignment Operator
template <typename T>
matrix<T>& matrix<T>::operator = (const matrix& right)
{
this->the_matrix= right.the_matrix;
this->rows = right.rows;
this->cols = right.cols;
this->spath = right.spath;
return *this;
}
// Overloaded << operator
template <typename T>
std::ostream& operator << (std::ostream& output, const matrix<T>& left)
{
// Test screen output to see if correct
std::cout << std::setw(14) << "The Matrix:" << '\n';
for( int a = 0; a < left.rows; ++a)
{
for( int b = 0; b < left.cols; ++b)
{
std::cout << ' ' << left.the_matrix[a][b] << ' ';
}
std::cout << '\n';
}
return output;
}
