#include <stdio.h>
#include <stdlib.h>
int main() {
float **p;
int m, n, i, j;
printf("Enter number of rows and columns: ");
scanf("%d%d", &m, &n);
/* Allocate memory */
p = (float *) malloc(sizeof(float *) * m); /* Row pointers */
for(i = 0; i < m; i++) {
p[i] = (float) malloc(sizeof(float) * n); /* Rows */
}
/* Assign values to array elements and print them */
for(i = 0; i < m; i++) {
for(j = 0; j < n; j++) {
p[i][j] = (i * 10) + (j + 1);
printf("%6.2f ", p[i][j]);
}
printf("\n");
}
/* Deallocate memory */
for(i = 0; i < m; i++) {
free(p[i]); /* Rows */
}
free(p); /* Row pointers */
}
Ref:http://www.annigeri.in/2011/11/dynamic-two-dimensioned-arrays-in-c.html
Same as above program:
int **array;
array = malloc(nrows * sizeof(int *));
if(array == NULL) {
fprintf(stderr, “out of memory\n”);
/*exit or return*/
for(i = 0; i < nrows; i++) {
array[i] = malloc(ncolumns * sizeof(int));
if(array[i] == NULL) {
fprintf(stderr, “out of memory\n”);
/*exit or return*/
}
}
Ref: http://www.writeulearn.com/memory-allocation-deallocation-2d-array/
same as above:
We can create an array of pointers also dynamically using a double pointer. Once we have an array pointers allocated dynamically, we can dynamically allocate memory and for every row like method 2.
#include <stdio.h>#include <stdlib.h>int main(){ int r = 3, c = 4, i, j, count; int **arr = (int **)malloc(r * sizeof(int *)); for (i=0; i<r; i++) arr[i] = (int *)malloc(c * sizeof(int)); // Note that arr[i][j] is same as *(*(arr+i)+j) count = 0; for (i = 0; i < r; i++) for (j = 0; j < c; j++) arr[i][j] = ++count; // OR *(*(arr+i)+j) = ++count for (i = 0; i < r; i++) for (j = 0; j < c; j++) printf("%d ", arr[i][j]); /* Code for further processing and free the dynamically allocated memory */ return 0;} |
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