eratosthenos

[Joe Smith]

It is nothing short of embarrassing to feel the need to ask for help on
this. I can't see how I would make the main control for this. What I want
is a for loop and a test condition. And while I know, from things I
pondered 2 decades ago, that a fella can write code without a goto, I'm
stuck.

/* sieve1.c */

#define whatever 20
#define N whatever
#include <stdio.h>

int main(void)
{
int i, A[N+1], m, sum;

/* initialize to 0 */

for (i = 0; i <= N; ++ i) A[i] = 0;

/* output */
printf("Primes less than N are:\n");
for (i = 2; i <= N; ++ i)
{
if (A[i] == 0)
printf("%d

[Barry Schwarz]

On Wed, 26 Apr 2006 19:14:03 -0400, "Joe Smith"
<gr**********@netzero.net> wrote:

It is nothing short of embarrassing to feel the need to ask for help on
this. I can't see how I would make the main control for this. What I want
is a for loop and a test condition. And while I know, from things I
pondered 2 decades ago, that a fella can write code without a goto, I'm
stuck.

/* sieve1.c */

#define whatever 20
#define N whatever
#include <stdio.h>

int main(void)
{
int i, A[N+1], m, sum;
If you change it to A[N+1]=0 you can eliminate the initialization loop
below.

/* initialize to 0 */

for (i = 0; i <= N; ++ i) A[i] = 0;
For each i that is not prime, you want to set A[i] to a non-zero
value. One way is

for (i = 2; i <= N; i++)
if (A[i] == 0)
for (j = i+i; j <= N; j += i)
A[j] = 1;


/* output */
printf("Primes less than N are:\n");
for (i = 2; i <= N; ++ i)
{
if (A[i] == 0)
printf("%d

It looks like the tail end of your program fell into the bit bucket.
Remove del for email

[Dave Thompson]

On Sat, 29 Apr 2006 17:07:56 -0700, Barry Schwarz <sc******@doezl.net>
wrote:

On Wed, 26 Apr 2006 19:14:03 -0400, "Joe Smith"
<gr**********@netzero.net> wrote:

int i, A[N+1], m, sum;

If you change it to A[N+1]=0 you can eliminate the initialization loop
below.

Must use braces for an array: ... A[N+1] = {0}
- David.Thompson1 at worldnet.att.net

[Joe Smith]

"Dave Thompson" <da*************@worldnet.att.net> wrote in message
news:uc********************************@4ax.com...

On Sat, 29 Apr 2006 17:07:56 -0700, Barry Schwarz <sc******@doezl.net>
wrote:

On Wed, 26 Apr 2006 19:14:03 -0400, "Joe Smith"
<gr**********@netzero.net> wrote:

>int i, A[N+1], m, sum;

If you change it to A[N+1]=0 you can eliminate the initialization loop
below.

Must use braces for an array: ... A[N+1] = {0}

Thanks. Down yonder I think I have this algorithm correct using static and
dynamic mem allocation. joe
-------------
character test here ??????