primes

#include <iostream>
using namespace std;

int Prime(int);
int main()
{
    cout << "Prime numbers from 1 to 10000 are: " << endl;

    int number;
    for(number = 1; number <= 100000; number++)
    {
        // Only print out the prime numbers
        if(Prime(number) == number)
            cout << number << " is prime!" << endl;
    }

    // Replaced system("pause"), why invoke another (Windows-only) program
    //  if you can do it using standard functions perfectly fine?
    cout << endl << "Press <enter> to exit..." << endl;
    cin.get();

    return 0;
}

int Prime(int number)
{
    for(int i = 2; i <= number / 2; i++)
    {
        if(number % i == 0)
            return i; // Abort, number is divisible by "i", thus not a prime
    }

    // Only return "number" when the entire for-loop completes
    // This means the number wasn't divisible by any number "i", hence prime
    return number;
}