Doubles Multiplication

[PaliiBenet]

So I am trying to get the perimeter of a regular polygon, but when I multiply the number of sides times the length of a side, its rounding. How do I keep it from rounding? I made both the side number and length doubles, and I tried using setprecision and fixed. What am I doing wrong?

  #include "stdafx.h"
#include <iostream>
#include <string>
#include "p.h"
#include <iomanip>

using namespace std;


int main() {
	double sides = 0.0;
	double length = 0.0;
	cout << "How many sides does the polygon have? ";
	cin >> sides;
	cout << "What is the length of the sides? ";
	cin >> length;
	Polygon pol;
	pol.set_value(sides, length);
	cout << "The perimeter of the polygon is: " << setprecision(5) << fixed << pol.polygonPerim() << endl;

	system("pause");
	return 0;
}

#pragma once
#include <iostream>
#include <string>
#include "stdafx.h"


using namespace std;

class Polygon {
public:
	//Setters and Getters
	void set_value(double, double);

	//Destructors
	Polygon();
	~Polygon();

	//Perimeter 
	double polygonPerim();
	

private:
	int _sides;
	string name;
	int _length;
};

#include "stdafx.h"
#include "p.h"


#include <iostream>

#include <string>

using namespace std;

//Constructors
Polygon::Polygon()
{
	_sides = 0.0;
	_length = 0.0;
}

//Destructors
Polygon::~Polygon()
{
}

//Setters and Getters
void Polygon::set_value(double sides, double length) {
	_length = length;
	_sides = sides;
}

//This will return the
//the perimeter of the 
//polygon.
double Polygon::polygonPerim() {
	return _sides * _length;
}

[Chervil]

line 47 and 49: int.

a regular polygon: number of sides should be an int. Only the length needs to be double.

int * double will give a double as the result.