The Obvious Method for Finding Primes

#include 
#include 
#include 
#include 

typedef  unsigned long long bignum;

void printPrime(bignum bn)
 {
 static char buf[1000];

 sprintf(buf, "%ull", bn);
 buf[strlen(buf) - 2] = '\0';
 printf("%s\n", buf);
 }

void findPrimes(bignum topCandidate)
 {
 bignum candidate = 2;
 while(candidate <= topCandidate)   
{    bignum trialDivisor = 2;   
int prime = 1;   
while(trialDivisor * trialDivisor <= candidate)    
{    if(candidate % trialDivisor == 0)     {     prime = 0;     break;     }    trialDivisor++;    }   if(prime) printPrime(candidate);   candidate++;   }  }  int main(int argc, char *argv[])  {  bignum topCandidate = 1000;  if(argc > 1)
  topCandidate = atoll(argv[1]);
 findPrimes(topCandidate);
 return 0;
 }