gistfile1.cpp

#include <iostream>
#include <fstream>
#include <cmath>
#include <stdlib.h>
using namespace std;

int main() {
    int data_size = 0; // size of data set
    int n = 0;   // Number to test for prime-ness
    int number_of_primes = 0;
    bool is_prime = true; // Boolean flag
    
    ifstream input("numbers.txt");

    if (!input) {
        cout << "Error in opening file. ";
    }

    string number;
    getline(input,number);

    //get first number which tells us how many numbers to test
    cout << number << endl;

    data_size = atoi(number.c_str());

    // test each number to see if it is prime
    for (int i = 0; i < data_size; i++)
    {
        input >> n;
        
        // TODO: Boolean flag, assume true until proven otherwise
        is_prime = true;

        // TODO: Test for prime by checking for divisibility
        //  by all whole numbers from 2 to sqrt(n).
        // If a number divides evenly, set your boolean flag to false
        for (int j = 2; j <= sqrt(n); ++j) {
            if (n % j == 0) {
                is_prime = false;
                break;
            }
        }
		
        // Print result of the test
        if (is_prime)
        {
            cout << n << " is prime." << endl;
            number_of_primes++;   
        }
        else
            cout << n << " is not prime." << endl;
    }

    cout << endl << "There were a total of " << number_of_primes
         << " prime numbers in the file." << endl;

    input.close();

    return 0;
}