Programming Forums > Application Development > Java

victor_shade · Oct 27th, 2005, 3:21 PM

I need help writting code that returns primes in an array, one method that returns the nth prime number

int getNthPrimeNumber(int n ){

}

and a second that returns the number of prime numbers less than or equal to n

int getNumberPrimeNumbers(int n) {

}

thanks in advance for the help

Mjordan2nd · Oct 27th, 2005, 4:08 PM

http://www.programmingforums.org/for...ighlight=prime

victor_shade · Oct 27th, 2005, 4:55 PM

thanks but that doesn't really help me I don't know how to chenge it to fit my program.

thanks though

2roll4life7 · Oct 27th, 2005, 5:13 PM

All you did was present us with your (likely homework) problem. You didn't tell us how you've already tried to solve the problem or provide us with any code you've started with (besides the function skeletons [that it looks like your teacher gave to you]). You havn't been specific enough either. Like what should the program do if there are no primes at all in the array? Throw an exception, bail, prompt the user, look in another array?

(Toggle Plain Text)

private boolean isPrime(int num) {
	int i = 2;
	while(i < num) {
		int j = num % i;
		if(j == 0)
			return false;
		else
			i++;
	}
	return true;
}

I'm providing you with one of the functions I've written that you'll obviously need. I left it uncommmented on purpose. If you can't figure out the rest of what you need to make those functions work, I suggest you take a different class.

victor_shade · Oct 27th, 2005, 5:48 PM

thank you for your help, I was able to get the other methods from the is prime method the thing I've been getting hung up on is the math part of isPrime, I had it messed up in a giant if statement which I see how stupid it was, I apologize for leaving such a vague question, and again thanks for the help

Oct 27th, 2005, 3:21 PM	#1
victor_shade Newbie Join Date: Oct 2005 Posts: 3 Rep Power: 0	finding primes in an array I need help writting code that returns primes in an array, one method that returns the nth prime number int getNthPrimeNumber(int n ){ } and a second that returns the number of prime numbers less than or equal to n int getNumberPrimeNumbers(int n) { } thanks in advance for the help

Oct 27th, 2005, 4:08 PM	#2
Mjordan2nd The Supreme Ruler Join Date: May 2004 Location: Houston Posts: 1,476 Rep Power: 6	http://www.programmingforums.org/for...ighlight=prime __________________ "Every gun that is made, every warship launched, every rocket signifies, in the final sense, a theft from those who hunger and are not fed, from those who are cold and are not clothed. The world in arms is not spending money alone. It is spending the sweat of its laborers, the genius of its scientists, the hopes of its children." - Dwight D. Eisenhower

Oct 27th, 2005, 5:13 PM	#4
2roll4life7 Programmer Join Date: Aug 2005 Location: 0x0010 * 0x0091 + 0x0004 Posts: 65 Rep Power: 4	All you did was present us with your (likely homework) problem. You didn't tell us how you've already tried to solve the problem or provide us with any code you've started with (besides the function skeletons [that it looks like your teacher gave to you]). You havn't been specific enough either. Like what should the program do if there are no primes at all in the array? Throw an exception, bail, prompt the user, look in another array? (Toggle Plain Text) private boolean isPrime(int num) { int i = 2; while(i < num) { int j = num % i; if(j == 0) return false; else i++; } return true; } private boolean isPrime(int num) { int i = 2; while(i < num) { int j = num % i; if(j == 0) return false; else i++; } return true; } I'm providing you with one of the functions I've written that you'll obviously need. I left it uncommmented on purpose. If you can't figure out the rest of what you need to make those functions work, I suggest you take a different class. __________________ (Toggle Plain Text) #if 0 /* in case someone actually tries to compile this / #if 0 / in case someone actually tries to compile this */ - libpng version 1.2.8 (example.c) <Jim_McNeat> Is there like a way to put a compiler in "Just trust me on that one" mode?

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Oct 27th, 2005, 4:55 PM	#3
victor_shade Newbie Join Date: Oct 2005 Posts: 3 Rep Power: 0	thanks but that doesn't really help me I don't know how to chenge it to fit my program. thanks though

Oct 27th, 2005, 5:48 PM	#5
victor_shade Newbie Join Date: Oct 2005 Posts: 3 Rep Power: 0	thank you for your help, I was able to get the other methods from the is prime method the thing I've been getting hung up on is the math part of isPrime, I had it messed up in a giant if statement which I see how stupid it was, I apologize for leaving such a vague question, and again thanks for the help

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Programming Forums > Application Development > Java

finding primes in an array