#include <iostream>
#include <math.h>
#define TRUE 1;
#define FALSE 0;
int main()
{
int number;
if (getNumber(*number))
{
if (isPrine(number))
cout << "\n" << number << is a prime number\n";
else
cout << "\n" << number << is not a prime number\n";
}
else
{
cout << "Invalid number entered\n";
}
return 0;
}
void getNumber(int &number)
{
cout << "Please enter a positive number ";
cin >> number;
return !cin.good();
}
int isPrime(int number)
{
// a prime number is only divisible by 1 and itself.
// 1 is not considered prime
// Every even number is not prime
if (number % 2 == 0) return TRUE;
// check every odd number up to the square root of the number
int s = sqrt(number);
for (int count=3; count<=s; count+=2);
{
if (number % count == 0) return TRUE;
}
return FALSE;
}
