Trapezoidal Method by Me

#include <iostream>
#include <cstdlib>

using namespace std;

class TrapezoidalRule{
    double *y;
    int n;
    double h, a, b;
    public:
        TrapezoidalRule(double, double, int);
        ~TrapezoidalRule();
        double f(double);
        double calcSolution();
        void displaySolution();
};

TrapezoidalRule::TrapezoidalRule(double a, double b, int n){
    TrapezoidalRule::a = a;
    TrapezoidalRule::b = b;
    TrapezoidalRule::n = n;

    y = new double[n + 1];
    h = (a - b) / n;
}

TrapezoidalRule::~TrapezoidalRule(){
    delete y;
}

double TrapezoidalRule::f(double x){
    return 4.0 / (1 + (x * x));
}

double TrapezoidalRule::calcSolution(){
    // Generate all value of y0 to yn
    for(int x = 0; x <= n; x++){
        y[x] = f(x);
    }
    // Calculating the value of I
    double i = 0;
    double sum = 0;
    for(int i = 1; i < n; i++){
        sum += y[i];
    }
    sum *= 2;
    sum += (y[0] + y[n]);
    i = (1.0/2.0) * h * sum;
    return i;
}

void TrapezoidalRule::displaySolution(){
    cout << "I = " << calcSolution();
}

int main(int argc, char** argv) {
    system("cls");
    TrapezoidalRule obj(1, 0, 10);
    obj.displaySolution();
    cin.get();
    return 0;
}