Matrix ADT

[Castiel1631]

I am trying to create an abstract data type for matrices. I have a function matrixInit to dynamically allocate memory for the structure and for the array. matrixCopy copies one matrix into another. there are functions to subtract, add and multiply matrices that return a pointer to memory where the Matrix structure is. I have included my .c file and my .h file below. I'm not exactly sure what's not working. I would appreciate it if someone could look at what I have and let me know where I'm going wrong. I believe that my first function is correct, and my destroy functions is also correct. I think the problem is in matrixCopy. I have also commented out sections so that everything would compile. the getelement function and setelement both cause segmentation faults and I can't figure out why.

# include <stdio.h>
# include <stdlib.h>
# include "matrix.h"

void matrixInit (Matrix* m , int r, int c)
{
	m= (Matrix*)malloc(sizeof(Matrix));
	int i, j;
	m->cols = c;
	m->rows = r;
	
	if (r != 0 & c != 0)
	{
		m ->element = (int**) malloc(sizeof(int*)*r);
	
		for (i = 0; i < r; i++)
		{
			m->element[i]= (int*) malloc( sizeof( int)*c);
				
			for(j=0; j<c; j++)
				{
					m->element[i][j]=0;
				}
		}
	}
	else
	{
		m->element= NULL;
	}
}

void matrixCopy (Matrix* m, Matrix* n)
{
	int i, j; 
	matrixDestruct(m);
	
	if( n->element !=NULL)
	{
		m ->element = (int**) malloc(sizeof(int*)*n->rows);
	
			for (i = 0; i < n->rows; i++)
			{
				m->element[i]= (int*) malloc( sizeof( int)*n->cols);
			
				for(j=0; j< n->cols; j++)
				{
					m->element[i][j] = n->element[i][j];
				}
			}
	}
}

int matrixGetElement (Matrix* m, int r, int c)
{
	//return m->element[r][c];
}

int matrixGetRows (Matrix* m)
{
	return m->rows;
}
	
int matrixGetCols (Matrix* m)
{
	return m->cols;
}
	
void matrixSetElement (Matrix* m, int r, int c, int v)
{
	//m->element[r][c]=v;
}
	
Matrix* matrixAdd ( Matrix* m, Matrix* n)
{/*
	int i, j;
	Matrix *k;
	k= (Matrix*)malloc(sizeof(Matrix));
	k->cols = m->cols;
	k->rows = m->rows;
	
	k ->element = (int**) malloc(sizeof(int*)*m->rows);
	
	for (i = 0; i < m->rows; i++)
		{
			k->element[i]= (int*) malloc( sizeof( int)*m->cols);
			for(j=0; j< m->cols; j++)
			{
				k->element[i][j] = n->element[i][j]+ m->element[i][j];
			}
		}
	return k;*/
}	
	
Matrix* matrixSubtract ( Matrix* m, Matrix* n)
{/*
	
	int i, j;
	Matrix *k;
	k= (Matrix*)malloc(sizeof(Matrix));
	k->cols = m->cols;
	k->rows = m->rows;
	
	k ->element = (int**) malloc(sizeof(int*)*m->rows);
	
	for (i = 0; i < m->rows; i++)
		{
			k->element[i]= (int*) malloc( sizeof( int)*m->cols);
			for(j=0; j< m->cols; j++)
			{
				k->element[i][j] = m->element[i][j] - n->element[i][j];
			}
		}

	return k;*/
}
	
Matrix* matrixMultiply( Matrix* m, Matrix* n)
{/*
	Matrix* k;
	int i, j, sum, x=0;

	k= (Matrix*)malloc(sizeof(Matrix));
	k->cols = m->cols;
	k->rows = m->rows;
	
	k ->element = (int**) malloc(sizeof(int*)*m->rows);
	
	for (i = 0; i < m->rows; i++)
		{
			k->element[i]= (int*) malloc( sizeof( int)*m->cols);
		}

	if(m->cols==n->rows )
	{
		for(i=0; i< (m->rows); i++)
		{	
			sum=0;
			for(j=0; j< (n->cols); j++)
			{
				sum+= m->element[i][j] * n->element[j][i];
				while(j==n->cols)
				{
					k->element[i][j]=sum;
				}
			}
		}

		return k;
	}
	else
		return NULL;*/
}
	
void matrixDestruct( Matrix* m)
{
	int i;
	if( m->element != NULL)
	{
		for ( i=0; i < m->rows; i++)
		{
			free(m->element[i]);
		}
	
			free(m->element);
	}

}

here is my .h file

typedef struct{
	int rows, cols;
	int **element;
}Matrix;

void matrixInit (Matrix* , int, int);
void matrixCopy (Matrix*, Matrix* );
int matrixGetElement (Matrix*, int, int);
int matrixGetRows (Matrix*);
int matrixGetCols (Matrix*);
void matrixSetElement (Matrix*, int, int , int);
Matrix* matrixAdd ( Matrix*, Matrix*);
Matrix* matrixSubtract ( Matrix*, Matrix*);
Matrix* matrixMultiply( Matrix*, Matrix*);
void matrixDestruct( Matrix*);

[Narue]

I think you should only work on one ADT library at a time unless you're already experienced with the task (which you clearly are not, no offense).

[Thaylo]

In C, the parameters of functions are passed by copy, always.
this mean you cant initialize a structure without a return. (like a void in this case)

(my English is poor, sorry)