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void PrintPrime(int n){
int[n+1] a;
a[0]=a[1]=0;
for(int i=2;i<n+1;i++)
a[i]=1;

for(i=2;i*i<n+1;i++)
if(a[i])
for(int j=i+1;j<n+1;j++)
if(a[j])
if(a[j]%a[i]==0)
a[j]=0;

for(i=0;i<n+1;i++)
{
if(a[i]) printf....
}

}

- Anonymous October 08, 2009 | Flag Reply

fuck yea!

- Anonymous October 08, 2009 | Flag Reply

{{{ primenumbers(int n) { primelist = (); i = 2; while (i < n) { bool = true; for each prime in primelist { if (i%prime == 0) { bool = false; break; } } if (bool == true) primelist.add(prime); } primelist.print(); } - Thiyaneshwaran S October 09, 2009 | Flag Reply

primenumbers(int n) {
  primelist = ();
  i = 2;
  while (i < n) {
    bool = true;
    for each prime in primelist {
      if (i%prime == 0) {
        bool = false;
        break;
      }
    }
    if (bool == true) primelist.add(i);
  }
  primelist.print();
}

- Thiyaneshwaran S October 09, 2009 | Flag Reply

I assume 500 is max number till which we find prime number. this can be modified for more flexibility.

#include <stdio.h>

int main (int argc, char *argv[])
{
    int n ;
    int i,j,res[500];

    n = atoi(argv[1]);

    for (i=0;i<=n;i++)
        res[i] = -1;


    for (i=2;i<=n;i++)
    {
        if (res[i] == -1)
        {
                res[i] = 1 ;
                for (j=2;(i*j)<=n;j++)
                res[i*j] = 0;
        }
    }


    for (i=2;i<=n;i++)
        if (res[i] == 1)
            printf ("%d ",i);

            return 0;
}

- Anonymous November 03, 2009 | Flag Reply

what should be the test cases?

- anon November 04, 2009 | Flag Reply

1) No need to check even numbers
2) 1 is not a prime
A C# program:

class Program
    {
        private static ArrayList primeList = new ArrayList();
        static void Main(string[] args)
        {
            getPrime(1);    // case 1: 1
            getPrime(2);    // case 2: 2
            getPrime(4);    // case 3: 4
            getPrime(197);  // case 4: a small prime itself
            getPrime(9999); ./ case 5: a middle nun-prime
            getPrime(65352); // a big one
            Console.Read();

        }

        static void getPrime(int n)
        {
            if (n < 2)
            {
                Console.WriteLine(" Number given {0} should greate than 1.", n);
                return;
            }

            primeList.Add(2);
            if (n >= 3)
            {
                primeList.Add(3);
            }
            int p = 3;
            do
            {
                p += 2;
                if (p > n) break;
                bool isPrime = true;
                for (int i = 1; i < primeList.Count; i++)
                {
                    if (p % (int)primeList[i] == 0)
                    {
                        isPrime = false;
                        break;
                    }
                }
                if (isPrime) primeList.Add(p);

            } while (p < n);
            Console.WriteLine(" Prime numbers less than {0}:", n);
            for (int i = 0; i < primeList.Count; i++)
            {
                Console.Write("{0} ,", (int)primeList[i]);
                if (i % 10 == 9)
                    Console.WriteLine();
            }
            Console.WriteLine();
            Console.WriteLine("---------------------------------");

        }

    }

- kulang November 27, 2009 | Flag Reply

en.wikipedia.org/wiki/Sieve_of_Eratosthenes

- Nithish April 19, 2010 | Flag Reply