## Algorithms

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Re: prime numbers Posted by indicatoto101 on 10 Nov 2004 at 9:04 PM
: This message was edited by gaetano at 2004-5-5 4:6:11

: please can anyone give me the algorithms for finding prime numbers below a number, given that number.
:

:
:
: The maybe easiest implementation for an algorithm which finds primes
: in a given range is the so-called "Sieve Of Erathostenes".
:
: - you will find really every prime
: - every found prime is 100% a prime
:
: - the array takes a lot of memory
: - the computation time is long for high ranges
:
: If you need the "sieve" in another language than C/C++, just use any
: search engine. You'll find everything you need ...
:

:
:
```
: #include <iostream>
: using namespace std;
:
: int
: main (void)
: {
: 	long	max;
: 	bool	*primes;
:
: 	cout << " Calculate prime numbers (sieve of Erathostenes)\n\n";
: 	cout << " Highest number to test: ";
: 	cin >> max;
:
: 	if (max < 2) {
: 		cerr << " Error: Invalid value!\n"
: 		     << "        Number must be greater than 2.\n";
: 		return 1;
: 	}
:
: 	// Create array and exclude 0 and 1
: 	primes = new bool[max + 1];
:
: 	// Fill list with all positive integers
: 	for (long i=0; i<=max; i++)
: 		primes[i] = true;
:
: 	// The testing ...
: 	for (long i=2; i<=max; i++)
: 		for (long j=2; i*j<max; j++)
: 			primes[i*j] = false;
:
: 	// The index of the array equals the numbers
: 	// If you want to look whether 7 is a prime, just try
: 	// if `(primes[7])'
:
: 	// Print them
: 	for (long i=2; i<=max; i++)
: 		if (primes[i])
: 			cout << i << endl;
:
: 	delete[] primes;
: 	return 0;
: }
: ```

:
:
:

Can you give me some pseudocode to Intel assembly? thanks didn't find it on google
paa_vvu prime numbers on 5 Apr 2004 at 7:28 PM
sekiz Re: prime numbers on 29 Apr 2004 at 4:31 PM
gaetano Re: prime numbers on 5 May 2004 at 4:05 AM
indicatoto101 Re: prime numbers on 10 Nov 2004 at 9:04 PM

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