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please help me!!!!

3 replies on 1 page. Most recent reply: Nov 16, 2005 12:14 AM by Matthias Neumair

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rey

Posts: 10
Nickname: zerocoal
Registered: Sep, 2005

please help me!!!!

Posted: Nov 14, 2005 9:39 PM

Write a program that stores the first 400 prime numbers in an array..

Please help me..i dont know how what is the formula of getting the prime numbers...
Thanks a lot..God Bless You all...

I will be expecting your reply...

Matthias Neumair

Posts: 660
Nickname: neumi
Registered: Sep, 2003

Re: please help me!!!!

Posted: Nov 14, 2005 10:45 PM

There is no real formula for prime numbers, only some rules.

1. All prime numbers except 2 are not even
2. If n1 is NOT a prime number, the result of n1 % [any previous prime number] can be 0.

So:
1. Use a Arraylist<Integer> to store the number. Later this will be very useful to create the array.
2. Put 2 into this list.
3. create a loop

Matthias Neumair

Posts: 660
Nickname: neumi
Registered: Sep, 2003

Re: please help me!!!!

Posted: Nov 16, 2005 12:12 AM

Well, seems I forgot to complete the answer.
Sorry about that

3. Create a loop from 3 to 400 stepwith 2: for (i = 0; i < 400; i+=2)
4. For every in the list stored prime number (called 'p') except 2 and p <= i / 3:
i is not a prime if the result of i % p == 0.
If this result is not 0 for all the p's, then add i to your ArrayList.

Matthias Neumair

Posts: 660
Nickname: neumi
Registered: Sep, 2003

Re: please help me!!!!

Posted: Nov 16, 2005 12:14 AM

Had an error in the loop code segment.
Here is the right one:

for (i = 3; i <= 400; i+=2)

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