#include <stdio.h>
#include <math.h>

int main()
{
   
   int limit = 250000000;
   
   int cur, i, j, sqrt_limit;
  
   //allocate the array 
   char *primes = (char *)malloc(limit+1);
   primes[0]='f';
   primes[1]='f';
  
   //initialize our sieve 
   for (i=2;i<=limit;i++)
      primes[i]='t';

   printf("List created\n");

   //using the int allows int to int compares and is faster than float to int
   sqrt_limit=(int)sqrt(limit);

   //outer loop for how high we need to test sqrt(limit) as w/ simple prime testing
   //if ensues we only do inner loop if i is a prime
   //inner loop crosses off the multiples

   for (i=2;i<=sqrt_limit;i++)
      if (primes[i]=='t') 
         for (j=i*2;j<=limit;j+=i)
            primes[j]='f';
/*
   for (i=2;i<=limit;i++)
      if (primes[i]=='t')
         printf("%d ",i);
*/

   free (primes);
   return 1;
}