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<vc7nb0$7rl3$1@paganini.bofh.team> View for Bookmarking (what is this?) Look up another Usenet article |
Path: ...!npeer.as286.net!npeer-ng0.as286.net!3.eu.feeder.erje.net!feeder.erje.net!newsfeed.bofh.team!paganini.bofh.team!not-for-mail From: Student Project <student@invalid.invalid> Newsgroups: alt.comp.lang.c, comp.lang.c Subject: A very slow program Date: Sun, 15 Sep 2024 22:45:59 +0000 Organization: To protect and to server Message-ID: <vc7nb0$7rl3$1@paganini.bofh.team> Mime-Version: 1.0 Content-Type: text/plain; Content-Transfer-Encoding: 7bit Injection-Date: Sun, 15 Sep 2024 22:33:05 -0000 (UTC) Injection-Info: paganini.bofh.team; logging-data="257699"; posting-host="ik8YFCuVdFDMks72ULyevQ.user.paganini.bofh.team"; mail-complaints-to="usenet@bofh.team"; posting-account="9dIQLXBM7WM9KzA+yjdR4A"; X-Notice: Filtered by postfilter v. 0.9.3 Content-Language: en Bytes: 1787 Lines: 38 #include <time.h> #include <stdio.h> #define RUNS 1000 #define SIZE 1000000 int mark[SIZE]; int main(void) { time_t start, finish; int i, loop, n, num; time(&start); /* This loop finds the prime numbers between 2 and SIZE */ for (loop = 0; loop < RUNS; ++loop) { for (n = 0; n < SIZE; ++n) mark[n] = 0; /* This loops marks all the composite numbers with -1 */ for (num = 0, n = 2; n < SIZE; ++n) if (!mark[n]) { for (i = 2 * n; i < SIZE; i += n) mark[i] = -1; ++num; } } time(&finish); printf("Program takes an average of %f seconds " "to find %d primes.\n", difftime(finish, start) / RUNS, num); } /* The result on my slow machine: Program takes an average of 0.018000 seconds to find 78498 primes. */