Factorials in C++ (with Comments)

factorial.cpp

/**
 * Copyright 2019 (c) Ralph Wilson Aguilar
 * For CS-111
 * Do not copy or redistribute without permission.
 */
#include <iostream>

int main ()
{   
    int factorial = 1, i, input;
    std::cout << "Enter the number you want to make a factorial of: ";
    std::cin >> input;

    /*
    * We use a Loop-based approach to get a number's factorial.
    * To get a factorial, we must first iterate it to a iterator
    * variable with a initialized value of 1.
    * 
    * The loop below is multiplying factorial from 1 to input's value. Where
    * we multiply from 1 to the input's value, this is also known as a range.
    */
    for (i=1; i <= input; i++)
    {
        factorial = factorial * i;
    }

    std::cout << "The factorial of " << input << " is " << factorial << std::endl;

    return 0;
}

factorial_while.cpp

#include <iostream>

int main ()
{
  int factorial=1, i=1, input;

  std::cout << "Input: ";
  std::cin >> input;

  // the way this loop works is that until i is less than or equal than
  while (i <= input)
  {
    factorial = factorial * i;
    // keep incrementing until our condition is met.
    i++;
  }

  std::cout << "The factorial of " << input << " is " << factorial << std::endl;
  return 0;
}