C: accessing members of struct in a function -
i'm trying use struct member 'size' in function print_shoe, loop doesn't run. however, if replace 'c->size' int in loop, runs fine
#include <stdio.h> #include <stdlib.h> #include <string.h> #define deck_size 52 #define num_faces 13 #define num_suits 4 #define length_faces 6 #define length_suits 9 typedef struct cards { char suits[num_suits][length_suits]; char faces[num_faces][num_faces]; int suit, face, card, value, size; int *values[num_faces]; } cards; char buf[101]; void print_shoe(); void init_decks(); int rand_int(); void shuffle(); int main(void) { srand( time(null) ); int decks_input = 0; int numberofdecks = 1; { printf("\nenter number of decks used in game (1-8):\n\n"); if (fgets(buf, sizeof(buf), stdin) != null) if (sscanf (buf, "%d", &decks_input)) numberofdecks = decks_input; } while (numberofdecks < 1 || numberofdecks > 8); cards *shoe = malloc(sizeof(cards) * numberofdecks * deck_size); shoe->size = numberofdecks * deck_size; shuffle(shoe); print_shoe(shoe); free(shoe); return 0; } void print_shoe(cards *c) { int i; (i = 0; < c->size; i++) { printf("card #%d = %s of %s\n", i+1, c->faces[c[i].face], c->suits[c[i].suit]); } } void init_decks(cards *c) { int i; (i = 0; < c->size; i++) { c[i].card = i; c[i].suit = c[i].card % num_suits; c[i].face = c[i].card % num_faces; } } void shuffle(cards *c) { init_decks(c); int i, j; cards tmp; (i = c->size - 1; > 0 ; i--) { j = rand_int(i + 1); tmp = c[j]; c[j] = c[i]; c[i] = tmp; } } int rand_int(int n) { int limit = rand_max - rand_max % n; int rnd; { rnd = rand(); } while (rnd >= limit); return rnd % n; } edit: question has been updated extensively in response comments needed more clarification
in revised code, have:
cards *shoe = malloc(sizeof(cards) * numberofdecks * deck_size); shoe->size = numberofdecks * deck_size; // need init_decks(shoe); here!!! shuffle(shoe); print_shoe(shoe); your code in print_shoe() printing, you've not initialized data malloc() other size, you're printing garbage. data returned malloc() uninitialized , must initialized before read. question changed while typing; still haven't called init_decks(shoe); need to.
this not why isn't working — i'm not sure problem — worth commenting on. have:
void shuffle(cards *c) { init_decks(c); int i, j; cards tmp; (i = c->size - 1; > 0 ; i--) { j = rand_int(i + 1); tmp = c[j]; c[j] = c[i]; c[i] = tmp; } } if you're going use c99 technique of declaring variables minimal scope, should writing:
void shuffle(cards *c) { init_decks(c); (int = c->size - 1; > 0; i--) { int j = rand_int(i + 1); cards tmp = c[j]; c[j] = c[i]; c[i] = tmp; } } (i wouldn't have missed call init_decks() had been written that.)
as noted in comment, cards structure rather top-heavy. allocate (for each card) enough space store ranks , suits possibly have. not necessary.
this code separates deck card. uses flexible array member in deck structure hold cards, convenient. may prefer use regular pointer there, in case you'll need pair of memory allocations , function deck_free() release memory allocated deck_alloc().
#include <stdio.h> #include <stdlib.h> #include <string.h> #include <time.h> #define num_faces 13 #define num_suits 4 #define deck_size (num_faces * num_suits) #define length_faces 6 #define length_suits 9 static const char suits[num_suits][length_suits] = { "clubs", "diamonds", "hearts", "spades" }; static const char faces[num_faces][num_faces] = { "ace", "deuce", "three", "four", "five", "six", "seven", "eight", "nine", "ten", "jack", "queen", "king", }; typedef struct card { int suit; int face; int card; } card; typedef struct deck { int size; card cards[]; // flexible array member } deck; void print_shoe(const deck *d); void init_decks(deck *d); int rand_int(int n); void shuffle(deck *d); static deck *deck_alloc(int numberofdecks); int main(void) { srand( time(null) ); int numberofdecks = 1; { char buf[101]; printf("\nenter number of decks used in game (1-8):\n\n"); if (fgets(buf, sizeof(buf), stdin) != null) { int decks_input; if (sscanf (buf, "%d", &decks_input)) numberofdecks = decks_input; } } while (numberofdecks < 1 || numberofdecks > 8); deck *shoe = deck_alloc(numberofdecks); shuffle(shoe); print_shoe(shoe); free(shoe); return 0; } static deck *deck_alloc(int numberofdecks) { deck *shoe = malloc(sizeof(deck) + (sizeof(card) * numberofdecks * deck_size)); if (shoe == 0) { fprintf(stderr, "out of memory\n"); exit(1); } shoe->size = numberofdecks * deck_size; return shoe; } void print_shoe(const deck *d) { (int = 0; < d->size; i++) printf("card #%d = %s of %s\n", i+1, faces[d->cards[i].face], suits[d->cards[i].suit]); } void init_decks(deck *d) { (int = 0; < d->size; i++) { d->cards[i].card = i; d->cards[i].suit = d->cards[i].card % num_suits; d->cards[i].face = d->cards[i].card % num_faces; } } void shuffle(deck *d) { init_decks(d); (int = d->size - 1; > 0 ; i--) { int j = rand_int(i + 1); card tmp = d->cards[j]; d->cards[j] = d->cards[i]; d->cards[i] = tmp; } } int rand_int(int n) { int limit = rand_max - rand_max % n; int rnd; { rnd = rand(); } while (rnd >= limit); return rnd % n; } sample output:
$ ./cards enter number of decks used in game (1-8): 1 card #1 = 8 of clubs card #2 = jack of clubs card #3 = deuce of diamonds card #4 = jack of hearts card #5 = queen of clubs card #6 = 4 of hearts card #7 = 6 of spades card #8 = king of hearts card #9 = 5 of spades card #10 = king of clubs card #11 = deuce of clubs card #12 = king of spades card #13 = 4 of spades card #14 = 9 of diamonds card #15 = 5 of hearts card #16 = deuce of spades card #17 = ten of clubs card #18 = 5 of diamonds card #19 = ten of spades card #20 = 3 of spades card #21 = 9 of hearts card #22 = 6 of clubs card #23 = ace of clubs card #24 = 3 of clubs card #25 = queen of hearts card #26 = jack of diamonds card #27 = 9 of clubs card #28 = 4 of clubs card #29 = 7 of spades card #30 = ace of diamonds card #31 = 6 of diamonds card #32 = 3 of hearts card #33 = queen of diamonds card #34 = ten of hearts card #35 = ten of diamonds card #36 = 7 of diamonds card #37 = 7 of clubs card #38 = deuce of hearts card #39 = ace of hearts card #40 = jack of spades card #41 = 8 of diamonds card #42 = 8 of spades card #43 = ace of spades card #44 = 3 of diamonds card #45 = queen of spades card #46 = 5 of clubs card #47 = 4 of diamonds card #48 = king of diamonds card #49 = 9 of spades card #50 = 8 of hearts card #51 = 6 of hearts card #52 = 7 of hearts $
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