[VB6]Prime Number Calculation (code help)

[Blufner]

Well my teacher is giving me two projects....this one is specifically supposed to be a challenge (and I agree) and the other thread which was pretty simple in the end.

I need to calculate all the prime numbers between 0 and 100.

For those that don't know what prime numbers are....

Prime numbers are numbers that can be divided by any number and will never equal a whole number.
.....
.....
.....
I think.

Is it possible for me to write..

If x/1 = INT then
      Bla bla bla
End if

can I write an If/Then statement saying if the numbers comes out an integer (No decimal places) then it does yada yada yada?

Help is always appreciated.

Thanks in advance.
~~Wymm

 

[s-p-n]

An int is any whole number/decimal.
You want to say:

If x/1 = REAL then
      Bla bla bla
End if

Replace REAL with whatever instance in that language you use for real numbers (numbers with no decimal)
Is this in C?

 

[Negata]

You should use modulo. For example, 12 mod 4 equals 0 as the remainder of the division, so it's not a prime, and obviously a prime mod any number other than 1 or itself never equals 0.

 

[-fedexer-]

If you haven't come to a solution by the time i'm home from school i'll assist you.

 

[Negata]

If you haven't come to a solution by the time i'm home from school i'll assist you.

If it's an assignment, shouldn't he do as much as possible by himself..?

 

[Blufner]

This project is different from the other. The other is for a grade. This isn't. This is in visual BASIC coding (@ s-p-n). Fed I would appreciate help. Negata thanks for trying but I have no idea what modulo is. We haven't even touched that. Fed PM me on msn when you're there ;3

 

[jMerliN]

Sieve, it is the best choice for this problem.

http://en.wikipedia.org/wiki/Sieve_of_Eratosthenes

You're welcome.

 

[Blufner]

Dude that is awesome. The answer is RIGHT THERE...Now I just need to sit for a while and think of how to write it in code. Thanks again.

Sincerely,
~~Wymm

 

[jMerliN]

Dude that is awesome. The answer is RIGHT THERE...Now I just need to sit for a while and think of how to write it in code. Thanks again.

Sincerely,
~~Wymm

It's a common algorithm, and a common implementation is to keep a list of current primes (start with adding 2), then iterate from 5 to n (n being your 100 here), then try to divide n by every number in your prime list up to the sqrt, using modulo, if the result is never 0 (ie, it's indivisible by any known primes), then it is prime, add it to the list, and continue.

 

[Blufner]

I have no idea what Modulo is though. I think I know why he gave me this as a challenge though. >_>...

 

[jMerliN]

I have no idea what Modulo is though. I think I know why he gave me this as a challenge though. >_>...

a Mod b

With both a and b being integer values, will give a modulus b. This is just the remainder after dividing a by b, so 5 mod 3 is 2, and 5 mod 7 is 5. If a mod b == 0, then a = n*b, for some integer n.