#include <iostream>
#include <cmath>
#include <climits>
#include <cstdlib>

using namespace std;

//define function prototypes
void printPrimes(int);
//int getBound();
bool numGood(string);
bool isPrime(int);

int main()
{
   int upBound;
   string usIn;
   bool inGood = false;

   //loop through until good input
   while(inGood == false)
   {
      //ask for upper bound
      cout << "Enter the upper bound of prime numbers you want printed: ";
      cin >> usIn;

      //check to see if num is good
      inGood = numGood(usIn);
   }

   //convert string to int
   upBound = atoi(usIn.c_str());

   //print prime numbers up to that point
   printPrimes(upBound);

   return 0; 
}

//check if user input is a good positive integer
//precondition:user has inputed a string for the number specified
//postcondition: the number is a valid floating point number or is not
//return:true if number is good, false if number is not good   
bool numGood(string input)
{
   for(int x = 0; x < input.size(); x++)
   {
      if(input[x] < 48 || input[x] > 57)
      {
	 cout << "Bad input, enter a new guess" << endl;
	 return false;
      }
   } 

   return true;
}

//check if number passed is prime and return t/f 
//precondition: the program has a number that it wants to know if it is prime or not
//postcondition: the number either is or is not a prime number
//return: true if number is prime, false if not
bool isPrime(int number)
{
   for(int i = 2; i < number/2 +1; ++i)
   {
      if(number%i == 0)
      {  
	 /* if divisible */
	 return false;
      }
   }

   /* if number is not divisible by anything
    * than it must be prime */
   return true;
}

//print all the numbers up to given bound that are prime
//precondition: User has told up to what number they want the primes printed
//postcondition: All prime numbers up to user specified have been printed to the screen 
//return: nothing.
void printPrimes(int bound)
{
   //loop through until upper bound
   for(int j = 3; j <= bound; j++)
   {
      //check if current increment is prime number and print if so
      if(isPrime(j) == true)
      {
	 cout << j << " is a prime number." << endl;
      }
   }
}