diff options
Diffstat (limited to 'randtest.c')
| -rw-r--r-- | randtest.c | 56 |
1 files changed, 38 insertions, 18 deletions
@@ -1,3 +1,12 @@ +/* + * Copyright (C) 2015 Tomasz Kramkowski <tk@the-tk.com> + * + * This program is free software. It is licensed under version 3 of the + * GNU General Public License. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see [http://www.gnu.org/licenses/]. + */ #include <stdint.h> #include <stdio.h> #include <stdlib.h> @@ -8,28 +17,39 @@ int8_t randrange(int8_t from, int8_t to) { - int base_random = rand(); - if (RAND_MAX == base_random) return randrange(from, to); - int range = to - from, - remainder = RAND_MAX % range, - bucket = RAND_MAX / range; - if (base_random < RAND_MAX - remainder) { - return from + base_random/bucket; - } else { - return randrange(from, to); - } + int base_random = rand(); + if (RAND_MAX == base_random) return randrange(from, to); + int range = to - from, + remainder = RAND_MAX % range, + bucket = RAND_MAX / range; + if (base_random < RAND_MAX - remainder) { + return from + base_random/bucket; + } else { + return randrange(from, to); + } +} + + +static unsigned rand_to_max(unsigned max) +{ + double random; + + while ((random = rand()) == (double)RAND_MAX); + + return random / (double)RAND_MAX * (double)max; } int main(int argc, char **argv) { - srand(time(NULL)); - int r; - uint16_t *amounts = calloc(sizeof(uint16_t), (TO - FROM + 1)); - for (int i = 0; i < 1000; i++) - amounts[randrange(FROM, TO) - FROM]++; + srand(time(NULL)); + + uint64_t counter[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0}; + + for (int i = 0; i < 1000000; i++) + counter[rand_to_max(9)]++; - for (int i = 0; i < TO - FROM + 1; i++) - printf("%d: %d\n", i, amounts[i]); + for (int i = 0; i < 10; i++) + printf("%d: %lu\n", i, counter[i]); - return 0; + return EXIT_SUCCESS; } |