/*This imports stuff from "iostream" which handles input and output.
In this case = input being the radius and output being the messages and the answer*/
#include <iostream>
using namespace std;

/*This defines stuff I use later on to make life easier, instead of typing 3.14159 every time I use it I can just type "PI"
NEWLINE is basically ENTER, and PI is, well, PI*/
#define PI 3.14159
#define NEWLINE '\n'

/*This is the "main" function, when I compile it, it looks for "main" first, so I put the stuff inside it*/
int main ()
{

    /*This declares the integers I am going to use later, "double" is a number that can also have a decimal point.
    if I just used "int" it would only accept whole numbers, so I used "double" so I could get a more accurate answer.*/
    double r;
    double circle;
    double h;

    /*"cout" means that it is going to print something on the screen, with the words in quotation marks being what gets printed
    First up it prints out what the program does*/
    cout << "Calculate the Circumference";
    /*Then it puts in new lines, or enters*/
    cout << NEWLINE;
    cout << NEWLINE;
    /*Then it asks you to enter a number*/
    cout << "Enter radius: ";
    /*It takes the number you just entered and stores it as the "double" of "r" which we declared above all this*/
    cin >> r;
    /*Then it does the calculation to get the answer*/
    circle = 2 * PI * r;
    /*It then takes the answer and prints it on the screen*/
    cout << "Circumference = ";
    cout << circle;
    cout << NEWLINE;

    /*This is to make it close, I forgot the code to make it close after you hit enter so I made this instead
    it takes input, stores it as "h" */

    cout << "To close type anything and press ENTER \n";
    cin >> h;

    /*Then if "h" equals anything, it "returns 0" which means "Close program"*/
    if(h){
        return 0;
    }
}