The PRIME NUMBERS

[Mango]

Mine got till the LONG overflow, that is up to and including 7FFFh
And just in 1,5 hour


It wasn't made in QB . However, these are the test results with my program made in QB:

1 min: 2,000,000
2 min: 4,031,482
1 h: 240,482,843

Hey Neo...I'm fiddling with C the last couple days...here's a c port of my basic primer finder...on my 1.5 GHz after 6 min, the biggest prime was 190,976,059. This looks similar to what you reported re flipping the signed 4-byte int after 1.5 hr...Mine uses unsigned, so I get to go all the way to ffffffff, instead of cutting short at 7fffffff. Cheers.

Code:

#include <iostream>

using namespace std;

int main()
{
    unsigned short inc = 1;
    unsigned long c;
    unsigned long x;
    unsigned long stop;
    unsigned long count=0;
    unsigned long hold=1;
    unsigned short array[6540]={3};
        
    
    cout << "Find primes up to what number?  (4,200,000,000 max)\n";
    cin >> stop;
    
    for (x=3; x<65536;x += 2)  //get small primes, put in array
    {      
        for (c=0; (x % array[c]) && (array[c]*array[c] < x)  ; c++);
        if (x % array[c])
        {
             //cout << x << " ";   //use this line to show all primes
             array[inc++]=x;
        }  
    }
    
    for (x=65537; x<stop;x += 2)  //find large primes
    {
        for (c=0; (x % array[c]) && (array[c]*array[c] < x)  ; c++);
        if (x % array[c])
        {
             //cout << x << " ";   //use this line to show all primes
             if (count++ > hold)
             {
             cout << x << " ";     //print every 100000th prime
             hold += 100000;
             }
        }  
    }
            
    cout << "\n done\n";
    return 0;
}