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/*(***********************************************************************)
(* *)
(* Objective Caml *)
(* *)
(* Pierre Weis, projet Cristal, INRIA Rocquencourt *)
(* *)
(* Copyright 2001 Institut National de Recherche en Informatique et *)
(* en Automatique. All rights reserved. This file is distributed *)
(* under the terms of the Q Public License version 1.0. *)
(* *)
(***********************************************************************)
(* Erathostene sieve, imperative version.
A vector is initialized with integers.
Then the vector is sieved. *)
*/
#include <stdio.h>
#define fixed_bound 5000000
long v[fixed_bound];
void sieve (long max) {
long i;
long j;
long prime_count = 0;
long prime;
for (i = 0; i < max; i++) {
v[i] = i + 1;
};
v[0] = 0;
prime_count = 0;
for (i = 0; i < max; i++) {
if (v[i] != 0) {
prime_count = prime_count + 1;
prime = i + 1;
for (j = i + prime; j < max; j = j + prime) {
if (j < max) {
v[j] = 0;
};
};
};
};
/* for (i = 0; i < max; i++) {printf ("%d ", v[i]);};*/
printf ("There are %d primes less than or equal to %d.\n", prime_count, max);
}
void main () {
sieve (fixed_bound);
}
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