Object values being reset

[Chamat]

I'm working with two classes and I find that everytime I call an object, their values are being reset to their initial values.

For my code below, if I call object1, modify its values, return to main, then call the object again, I can see that their values have reset and I don't know what's causing this.

#include <iostream>
#include <iomanip>
using namespace std;
#include "Circles.h"
void menu();
void operations(Circles sphere);


int main()
{
	Circles sphere1;
	Circles sphere2;
	
	while (true) {
		cout << "Which circle would you like to interact with, or find the distance between the 2 circles? [1|2|3] \n ";
		int op;
		cin >> op;
		if (op == 1) {
			menu();
			operations(sphere1);
		}
		else if (op == 2) {
			menu();
			operations(sphere2);
		}
		else if (op == 3) {
			double distance = sphere1 - sphere2;
			cout << "The distance between the two circles is: " << fixed << setprecision(3) << distance << endl;
			break;
		}
		else {
			cout << "Invalid entry\n";
			break;
		}
	}
	system("pause");
	return 0;
}

void menu() {
	cout << "Which Operation would you like to perform?\n" << " 1: Set Center\n " << "2: Set Radius \n " << "3: Get Center \n " << "4: Get Radius \n " << "5: Get Circumference \n " << "6: Get Area \n " 
		<< "7: Return to main \n ";
}

void operations(Circles sphere) {
	int x1, y1;
	int radius;
	double rad = sphere.getRadius();
	double circumference = sphere.calcCircumference();
	double area = sphere.calcArea();
	int op;
	while (true) {
		cin >> op;
		switch (op) {
		case 1:
			cout << "enter x coordinate: ";
			cin >> x1;
			cout << "enter y coordinate: ";
			cin >> y1;
			sphere.setCenter(x1, y1);
			menu();
			break;
		case 2:
			cout << "Enter Radius: ";
			cin >> radius;
			sphere.setRadius(radius);
			menu();
			break;
		case 3:
			sphere.printStats();
			menu();
			break;
		case 4:
			cout << "Radius: " << rad << endl;
			menu();
			break;
		case 5:
			cout << "Circumference " << circumference << endl;
			menu();
			break;
		case 6:
			cout << "Area: " << area << endl;;
			menu();
			break;
		case 7:
			return;
		default:
			cout << "Invalid entry\n";
			break;
		}
	}
}

and if it helps here are my header and implementation files for my class

#include <iostream>

using namespace std;

#ifndef CIRCLES_H
#define CIRCLES_H
class Circles{
public:
	Circles(double r);    // Constructor
	Circles();             // Default constructor
	Circles(double r, int c1, int c2);

	void setCenter(int x, int y);
	double calcArea();
	double calcCircumference();
	void printStats();     // This outputs the radius and center of the circle.
	void setRadius(double r);
	double getRadius() const;

	double Circles::operator-(const Circles &r) const;


private:
	double  radius;
	int     center_x;
	int     center_y;
};
#endif 

#include "stdafx.h"
#include "Circles.h"

Circles::Circles()
{
	radius = 1;
	center_x = 0;
	center_y = 0;
}

Circles::Circles(double r)
{
	radius = r;
}
Circles::Circles(double r, int c1, int c2) {
	radius = r;
	center_x = c1;
	center_y = c2;
}

double Circles::calcArea()
{
	const double PI = 3.14;
	return PI * radius * radius;
}

double Circles::calcCircumference()
{
	const double PI = 3.14;
	return 2 * PI * radius;
}

void Circles::printStats()
{
	cout << "The center of the circle is " << center_x
		<< "   " << center_y << endl;
}

void Circles::setCenter(int x, int y)
{
	center_x = x;
	center_y = y;
}

void Circles::setRadius(double r) {
	radius = r;
}

double Circles::getRadius() const {
	return radius;
}

double Circles::operator-(const Circles &r) const {
	double xval = (r.center_x - center_x)*(r.center_x - center_x);
	double yval = (r.center_y - center_y)*(r.center_x - center_x);

	double distance = sqrt(xval + yval);

	return distance;
}

[TheIdeasMan]

When one calls a function, it receives copies of the arguments. To fix your situation, pass the parameters by reference:

void operations( Circles& sphere) {

The operations function relies on the menu function being called immediately before it, which isn't ideal. The code could break quite easily if modified. I like to put the switch and menu function call inside a while loop controlled with a boolean Quit:

bool Quit = false;

while (!Quit) {
   menu(); // with quit option
   // get input
   switch(input) {
      // cases
    4:  // Quit case
        Quit = true;
        break;
    default:
     // default behaviour
    } // end switch

   } // end while 

You have the PI const in there twice. You could make it global, but a better practise is to put it in a header file. constexpr is stronger than const, so use that if you can.

Use const wherever you can, especially for function parameters:

Circles::Circles(const double r, const int c1, const int c2) { // why are the centre values int?

Finally I like to put digits before and after the decimal point to reinforce the idea that it is a double:

2.0 * PI * radius;

It can help avoid integer math especially with division, and it at least saves the compiler an implicit conversion from integer to double.

[Chamat]

Thanks for the help.

And the advice is appreciated, thank you!