prime sieve in C

#include <stdio.h>
#include <malloc.h>

int nextPrime(int i, char *sieve, int max) {
   while(i < max && !sieve[i]) {
      i++;
   }
   return i;
}
void setNotPrime(int i, char *sieve, int max) {
   int j;
   for(j = i; j < max; j += i) {
      sieve[j] = 0;
   }
}

int main(int argc, char**argv) {
   int n = atoi(argv[1]);
   char *sieve = (char*) malloc(sizeof(char));
   int i;
   for(i = 0; i < n; i++) {
      sieve[i] = 1;
   }

   for(i = 2; i < n; i = nextPrime(i, sieve, n)) {
      printf("%d ", i);
      setNotPrime(i, sieve, n);
   }
                                                                                                                                               
   return 0;
}