Thread: A question related to dynamic memory allocation

Hi,

I have a really basic question about dynamic memory allocation. Is it necessary to free memory allocated to matrix temp (in function transpose) ?

Code:

#include<stdio.h>
#include<stdlib.h>
#include<conio.h>

struct dMat {
	int rows;
	int cols;
	double **t;
};

struct dMat allocate(int rows, int cols)
{
	struct dMat t;
	int i;
	t.rows=rows;
	t.cols=cols;
	t.t=(double **)malloc(t.rows * sizeof(double *));
	for(i = 0; i < t.rows; i++)
		t.t[i] = (double *) malloc(cols * sizeof(double));
	return t;
}

struct dMat transpose(struct dMat t)
{
	struct dMat temp;
	int i, j;
	temp.cols = t.rows;
	temp.rows = t.cols;
	temp = allocate(temp.rows, temp.cols);

	for(i=0; i<temp.rows; i++)
		for(j=0; j<temp.cols; j++)
			 *(*(temp.t+i)+j)=*(*(t.t+j)+i);

	return temp;
}

void display(struct dMat t){
	int i,j;
	for(i=0;i<t.rows;i++) {
		for(j=0;j<t.cols;j++)
			printf("%.3f ",*(*(t.t+i)+j));
		printf("\n");
	}
	printf("\n");
   printf("Dimension = [%d, %d]\n\n", t.rows, t.cols);
}

int main() {
	struct dMat beta;
	int i, j;

	beta.rows = 5;
	beta.cols = 6;
	beta = allocate(beta.rows, beta.cols);

	for(i = 0; i < beta.rows; i++)
		for(j = 0; j < beta.cols; j++)
			*(*(beta.t+i)+j) = 2.5*(i+j);

	display(beta);
	display(transpose(beta));
    free(beta.t);
    getch();
	return 0;
}