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#include <iostream>
#include <iomanip>
#include <string>
#include <cmath>
using namespace std;
string anstolower(string s)
{
string result = "";
for(int i = 0; i < s.length(); i++)
{
result += tolower(s[i]);
}
return result;
}
int main()
{
// ========!===============!===============!===============!===============!========
// VARIABLES
// ========!===============!===============!===============!===============!========
unsigned int num, test; // Number user chooses to test, value testing primality.
unsigned int factor, outcome; // Number of factors found, value to determine if a factor.
unsigned int halfNum; // Half of the input number.
int primeNum=1; // Number of prime factorizations performed.
string input; // User input for Yes/No question.
string low; // tolower'd form of input.
// ========!===============!===============!===============!===============!========
// GREETINGS
// ========!===============!===============!===============!===============!========
// Welcome the user.
cout << "\n\n ===============!===============!===============!==============="
<< "\n ~!~ Welcome to the Prime Factorizationing ~!~"
<< "\n ===============!===============!===============!==============="
<< "\n\n This program will calculate the primality of a number, and if it is"
<< "\n not prime, the factors and number of factors of the input number.";
// START OF PROGRAM END CHECK LOOP
do {
// START OF PROGRAM LOOP.
do {
// Reset testing variables to allow computation for new numbers.
test=2; // Sets the starting divisor to 2 to begin testing for factors.
factor=0; // Sets the number of factors of the input number to zero.
// Numbers each factorization for easier following.
cout << "\n\n\n Prime Number Test # " << setw(2) << primeNum << "";
// Increases the number for record of later factorizations.
primeNum ++;
// ========!===============!===============!===============!===============!========
// USER INPUT
// ========!===============!===============!===============!===============!========
// Prompt user for number to be tested.
cout << "\n\n Please input a number to calculate if it is prime. : ";
cin >> num;
// ========!===============!===============!===============!===============!========
// CALCULATION
// ========!===============!===============!===============!===============!========
// START OF FACTOR FINDING LOOP.
do {
halfNum = num/2;
// If outcome does not equal zero, test was a factor of the number.
outcome = num%test;
// If outcome does not equal zero, shows the user the found factor.
if (outcome == 0) {
// PROBLEM WITH CALCULATION OF SQUARE ROOTS.
// If test is equal to half of the input number and it is a factor, it is the square
// root of the number, so only 1 factor was found.
if (test == halfNum) {
// The test number was the factor found, so show test.
cout << "\n " << setw(10) << test << " is a factor of " << num << ".";
// There was only 1 factor, so factor increases by 1.
factor++;
}
// If the found factor was not half of the input number, then two factors were found.
else {
// Test number and its sister factor, found by (num/test), are displayed.
cout << "\n " << setw(10) << test << " and " << (num/test) << " are factors of "
<< num << ".";
// There were 2 factors found, so factor increases by 2.
factor += 2;
}
}
// Increases the test variable by 1 for the loop to continue.
test++;
/* (test <= (num/test)) keeps test values smaller than otherwise since the numbers over num/2
were previously calculated. */
// END OF FACTOR FINDING LOOP
} while (test <= (num/test));
// ========!===============!===============!===============!===============!========
// FINAL OUTCOME
// ========!===============!===============!===============!===============!========
// Inform user of the outcome.
cout << "\n\n ===============!===============!===============!===============";
// SINCE THERE IS AN UNRESOLVED PROBLEM WITH SQUARE ROOTS UPSTREAM, THIS SECTION IS FLAWED.
// If there was only 1 factor, display that factor (test was increased by 1 before the loop
// terminated, so to find the factor it is (test1).
if (factor == 1) {
cout << "\n The only factor of " << num << " is " << (test1) << " (excluding"
<< " 1 and " << num << ").";
}
// If there was more than one factor, display the number of factors found.
else if (factor != 0) {
cout << "\n There are " << factor << " factors of " << num << " (excluding"
<< " 1 and " << num << ").";
}
// If there were no factors, input number is prime.
else {
cout << "\n The input number is prime." << endl;
}
cout << "\n ===============!===============!===============!===============";
// Prompt for calculation of primality of a new number or to terminate program.
cout << "\n\n Would you like to calculate the primality of a new number? Yes or No? : ";
cin.ignore();
getline(cin,input);
// Validate input.
low = anstolower(input);
while((low != "y") && (low != "yes") && (low != "n") && (low != "no")) {
cout << " Invalid choice. Please choose Yes or No. : ";
getline(cin,input);
low = anstolower(input);
}
// END OF PROGRAM LOOP
} while ((low == "yes")  (low == "y"));
// Check to see if the user wanted to terminate program.
cout << "\n Are you sure? Type Yes to close program, No to calculate the primality of a"
<< "\n\tnew number. : ";
getline(cin,input);
// Validate input.
low = anstolower(input);
while((low != "y") && (low != "yes") && (low != "n") && (low != "no")) {
cout << " Invalid choice. Please choose Yes or No. : ";
getline(cin,input);
low = anstolower(input);
}
// END OF PROGRAM END CHECK LOOP
} while ((low == "no")  (low == "n"));
return 0;
}
 