Prime Number Finder

#include <iostream>
using namespace std;

int main()
{
   bool prime;
   int number,remainder,divisor;
    
   cout<< "Welcome to the Prime Number Finder\n\n";
   for (number=0; number < 2147483648; number++) {
      prime = true;
      for (divisor=2; divisor < number; divisor++) {
         if (!(number % divisor)) {
            prime = false;
            break;
         }   
      }   
      if (prime)
         cout<< number << " is prime\n";
   }   
      
   cin.get();
   return 0;
} 

#include <cmath>

/* sieve() - a function that takes an array of booleans 
   and the size of the array 
   The function fills the array and returns a pointer to the
   array 
   The caller is responsible for ensuring that the buffer 
   is at least 'range' size of larger) 
*/

bool* sieve(int range, bool[] found)
{
    int maxtest;  

    maxtest = ceil(sqrt(range)); // the largest value that needs to be tested  
    
    // pre-set the values of zero and one to false
    found[0] = false;
    found[1] = false;

    // set the remaining values to true by default
    // we do not treat 2 as a sepcial case, since the
    // mechanism of the algorithm will have the
    // same effect anyway.
    for (int i = 2; i < range; ++i)
    {
         found[++i];
    }

    for (int test = 2; test < maxtest; ++test)
    {
          // If a value to be tested has not been 'crossed out' 
         // by the time the loop reaches it, then it is prime.
         if (found[test])
         {
              // when a prime has been found, find each
              // multiple of it in the array, and set it to false
             
              for (int lastval = test * 2; lastval < range; lastval += test)
              {
                 found[lastval]  = false;
              }
         }
     }
     return found;
}

#include <iostream>
#include <stdio.h>
#include <conio.h>
using namespace std;
int main()
{
    bool prime;
    int number, remainder, divisor;
    cout<<"Welcome to the PrimeNumberFinder\n";
    cout<<"2 is prime\n";
    for (number = 3; number < 10000000; number += 2){
        prime = true;
        for (divisor = 3; divisor < (number / 2); divisor++){
            remainder = (number % divisor);
            if (remainder == 0){
                prime = false;
                break;}
        }    
        if (prime == true){
            cout<< number << " is a prime\n";
            }     
    }
    getch();
    return 0;
}

        for (divisor = 3; divisor < (number / 2); divisor++){
            remainder = (number % divisor);

int numroot= sqrt(number);//find the root of number once instead each time through the nested loop.
   for (divisor = 3; divisor <= numroot; divisor++){
      remainder = (number % divisor);