I miss C programming. Program to find prime numbers


Uses unsigned long long, goes up to ULONG_LONG_MAX.

Intel Core Duo 2 processor, running Cygwin on Windows XP, and compiled using gcc 3.4.4. Stops at first million results due to time. Can reasonably get to 10 million, if you’re willing to wait.


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

int main(int argc, char **argv)
{
unsigned long long divisor, max_divisor, prime_test;
int break_time = 0;

printf("%llun", 2LL);
for(prime_test = 3LL; prime_test < ULONG_LONG_MAX; prime_test+=2LL)
{
max_divisor=1LL+sqrt(prime_test);
for(divisor=3LL;divisor <= max_divisor; divisor+=2LL)
{
if(prime_test % divisor == 0)
{
break;
}
}
if(divisor >= max_divisor)
{
printf("%llun", prime_test);
}
else
{
continue;
}
break_time++;
if(break_time == 999999)
{
break;
}
}
return 0;
}
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