#include <stdio.h>
#include <stdlib.h>

typedef enum {PRIME, COMPOSITE} Primality;

void GeneratePrimes(int bound) {
  Primality sieve[bound];
  int test, mark;
  // Start by marking everything as prime.
  for (mark = 2; mark < bound; ++mark) {
    sieve[mark] = PRIME;
  }
  for (test = 2; test < bound; ++test) {
    switch (sieve[test]) {
      case PRIME:
        for (mark = test * 2; mark < bound; mark += test) {
          sieve[mark] = COMPOSITE;
        }
        printf("%d is prime\n", test);
        break;
      case COMPOSITE:
        printf("%d is composite\n", test);
        break;
    }
  }
}

int main() {
  GeneratePrimes(100);
  return EXIT_SUCCESS;
}