Snippet: Prime Number Generator

[iSDK]

Hi,

I promised one of my friends I would make this for him, as he spent a long time creating a python algorithm to work it out and then realised python cannot run on iPhones!

Please do not take this code, and make a Prime Number generating application.


So here is the code:

Finder.h:

- (int)getPrimeNumberofLength:(int)length;

Finder.m

- (int)getPrimeNumberofLength:(int)length {
    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
	int primenumber, d;
    BOOL isPrime;
    
    for (primenumber = 2; primenumber <= length; ++primenumber)
    {
        isPrime = YES;
        
        for (d = 2; d < primenumber; ++d)
        {
            if (primenumber % d == 0)
                isPrime = NO;
        }
		
        if (isPrime)
			
		NSLog(@"%i", primenumber);
    }
    
    [pool drain];
    return 0;
}

Please do not take this code, and make a Prime Number generating application.

[Kalimba]

Originally Posted by iSDK

- (int)getPrimeNumberofLength:(int)length {
    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
	int primenumber, d;
    BOOL isPrime;
    
    for (p = 2; p <= length; ++p)
    {
        isPrime = YES;
        
        for (d = 2; d < primenumber; ++d)
        {
            if (primenumber % d == 0)
                isPrime = NO;
        }
		
        if (isPrime)
			
		NSLog(@"%i", primenumber);
    }
    
    [pool drain];
    return 0;
}

[/BOLD]

This code won't compile as it is. Also, there some a couple minor optimizations that can be made to make the code run faster.

[iSDK]

Hey, Thanks for the feedback. Its wierd, as it works for me and my friend. What seems to be the reason why it wont compile?

Thanks again.

Originally Posted by Kalimba

This code won't compile as it is. Also, there some a couple minor optimizations that can be made to make the code run faster.

[Kalimba]

Originally Posted by iSDK

Hey, Thanks for the feedback. Its wierd, as it works for me and my friend. What seems to be the reason why it wont compile?

Thanks again.

The variable "p" in your for loop is never declared. My guess is that it should be the variable "primenumber" instead.

[iSDK]

Yup, thats correct. I had previously edited the code, and that line had obviously escaped my eyes... The code is now fixed, and working.

Originally Posted by Kalimba

The variable "p" in your for loop is never declared. My guess is that it should be the variable "primenumber" instead.