#include #include int **mtrx_calloc (size_t m, size_t n); /* initialize elements to 0 */ int **realloc_rows (int **ap, size_t *m, size_t n, size_t newm); /* resize newm x n */ void mtrx_prn (size_t m, size_t n, int **matrix); /* print matrix with/pad */ void mtrx_free (size_t m, int **matrix); /* free memory allocated */ int main (int argc, char **argv) { /* set initial size from arguments given (default: 3 x 4) */ size_t m = argc > 2 ? (size_t)atoi (argv[1]) : 3; size_t n = argc > 2 ? (size_t)atoi (argv[2]) : 4; /* allocate the m x n matrix */ int **matrix = mtrx_calloc (m, n); /* fill with misc values */ register size_t i = 0, j = 0; for (i = 0; i < m; i++) { for (j = 0; j < n; j++) matrix [i][j] = (int)(i + j); } /* print matrix */ printf ("\nThe dynamically allocated %zux%zu matrix is:\n\n", m, n); mtrx_prn (m, n, matrix); /* reallocate matrix - add 4 rows */ printf ("\nReallocate matrix to %zux%zu:\n\n", m + 4, n); size_t oldm = m; matrix = realloc_rows (matrix, &m, n, m + 4); /* fill new rows with misc values */ for (i = oldm; i < m; i++) { for (j = 0; j < n; j++) matrix [i][j] = (int)(i + j); } mtrx_prn (m, n, matrix); /* free memory alocated */ mtrx_free (m, matrix); /* just to make it look pretty */ printf ("\n"); return 0; } /* allocate/initialize mxn matrix */ int **mtrx_calloc (size_t m, size_t n) { register size_t i; int **array = calloc (m, sizeof *array); if (!array) { /* validate allocation */ fprintf (stderr, "%s() error: memory allocation failed.\n", __func__); exit (EXIT_FAILURE); } for (i = 0; i < m; i++) { array[i] = calloc (n, sizeof **array); if (!array[i]) { /* validate allocation */ fprintf (stderr, "%s() error: memory allocation failed.\n", __func__); exit (EXIT_FAILURE); } } return array; } /* realloc an array of pointers to int* setting memory to 0. */ int **realloc_rows (int **ap, size_t *m, size_t n, size_t newm) { if (newm <= *m) return ap; size_t i = 0; int **tmp = realloc (ap, newm * sizeof *ap); if (!tmp) { fprintf (stderr, "%s() error: memory reallocation failure.\n", __func__); // return NULL; exit (EXIT_FAILURE); } ap = tmp; for (i = *m; i < newm; i++) { ap[i] = calloc (n, sizeof **ap); if (!ap[i]) { /* validate allocation */ fprintf (stderr, "%s() error: memory allocation failed.\n", __func__); exit (EXIT_FAILURE); } } *m = newm; return ap; } /* print a (m x n) matrix (check pad alloc) */ void mtrx_prn (size_t m, size_t n, int **matrix) { register size_t i, j; for (i = 0; i < m; i++) { char *format = "[ %2d"; for (j = 0; j < n; j++) { printf (format, matrix [i][j]); format = ", %2d"; } puts(" ]"); } } void mtrx_free (size_t m, int **matrix) { register size_t i; for (i = 0; i < m; i++) { free (matrix [i]); } free (matrix); }

[TUTORIAL] ➡️ matrix in C