Understanding the HCF Algorithm in C++
This C++ program calculates the HCF (Highest Common Factor) using user input and
the Fast HCF C++ Code from the previous lesson.
Let's add some input mechanism so our user enters the set of
numbers whose H.C.F. we are to find.
Combining the H.C.F. (G.C.D.) C++ Code and Collecting User Input
All we need is a main class C++ code that asks the user for input.
For this purpose, we'll use the getline() and cin
objects.
How to use the HCF Code in C++
The user gets to enter his/her choice of numbers for the HCF C++ algorithm.
After entering each number, the user presses <Enter>.
After the user has entered every of his/her numbers, the
user enters the word done
to see the result.
Note: You can comment out the C++ code for the main class from the previous lesson if you have been following.
So! C++ Fun Practice Exercise - Find HCF with User Input
As a fun practice exercise, feel free to try out your own numbers, and see how the C++ code finds the HCF of your input numbers.
C++ Code for HCF with User Input - Main Class.
//
#include "stdafx.h"
#include "FastHCF.h"
#include <iostream>
#include <vector>
#include <string>
#include <sstream>
#include <regex>
using namespace std;
int main() {
try {
cout << "\n Welcome to our demonstration sequels\n";
cout << "Hope you enjoy (and follow) the lessons.\n\n";
vector<unsigned> set;
// Collect input
cout << "\nWelcome to our Find HCF program.\n";
cout << "Enter your series of numbers whose HCF you wish to find.\n";
cout << "\nType 'done' when you are through with entering your numbers.\n";
cout << "Enter First Number: ";
set = {};
string user_input;
int user_num;
regex verify_num("([0-9]+)"); //Regular expression object
try {
do {
// get keyboard input
getline(cin, user_input);
// Convert 'user_input' to upper case.
transform(user_input.begin(), user_input.end(), user_input.begin(), ::toupper);
// Make sure input is a number
if (regex_match(user_input, verify_num)) {
stringstream(user_input) >> user_num;
if (user_num != 0) {
set.push_back(user_num);
cout << "Enter Next Number: ";
}
else {
cout << "\nYou cannot enter zero. Repeat that!\nType 'done' when you're finished.\n";
}
}
else if (user_input != "DONE") {
cout << "\nWrong Input. Repeat that!\nType 'done' when you're finished.\n";
}
} while (user_input != "DONE");
}
catch (exception& ex) {
throw "Bad Input";
}
// use the fast class to create object
FastHCF H_C_F(set);
cout << "\n" << H_C_F.getHCF() << "\n";
} catch (exception& e) {
cout << "\n" << e.what() << "\n";
}
return 0;
}