/*////////////////////////////////////////////////////////
// Name: Peter M. Maurer
// Program: Sieve of Eratosthenes
// Due: Never
// Language: B
////////////////////////////////////////////////////////*/

main()
{
	/* define the sieve data structure */
	auto Candidates[1000],i,j;
	i = 0;
	while (i<1000)
	{
		/* everything is potentially prime until proven otherwise*/
		Candidates[i] = 1;
		i++;
	}
	/* Neither 1 nor 0 is prime, so flag them off*/
	Candidates[0] = 0;
	Candidates[1] = 0;
	/* start the sieve with the integer 0*/
	i = 0;
	while (i<1000)
	{
		/* advance to the next un-crossed out number.*/
		/* this number must be a prime*/
		while (i<1000 & Candidates[i] == 0)
		{
			i++;
		}
		/* insure against running off the end of the data structure*/
		if (i<1000)
		{
			/* cross out all multiples of the prime, starting with 2*p.*/
			j = 2;
			while (j*i < 1000)
			{
				Candidates[j*i] = 0;
				j++;
			}
			/* advance to the next candidate*/
			i++;
		}
	}
	/* all uncrossed-out numbers are prime (and only those numbers)*/
	/* print all primes*/
	i = 0;
	while (i<1000)
	{
		if (Candidates[i] != 0)
		{
			putnumb(i);
			putchar(' is ');
			putchar('prim');
			putchar('e*n');
		}
		i++;
	}
}