Tutor 4

#include <iostream>
#include <cmath>

using namespace std;

class Quadratic{

public:
    Quadratic(){}
    Quadratic(double, double, double);
    double overload () const;
    double root() const;
    double range (double, double, double) const;

private:
    double a,b,c;

friend istream& operator>>(istream&, Quadratic&);
friend ostream& operator<<(ostream&, const Quadratic&);
};

 Quadratic::Quadratic(double A, double B, double C)
{
    a=A;
    b=B;
    c=C;
}

double Quadratic::overload() const
{
    if (a == 0){
        cout<<"The function is not quadratic"<<endl;
        return 1;}
    else
        return 0;
}

double Quadratic::root() const
{
    double x1,x2,determinant;
    determinant= b*b - 4*a*c;

    if(determinant>0)
    {
        x1=(-b + sqrt(determinant))/(2*a);
        x2=(-b - sqrt(determinant))/(2*a);
        cout<<"The function has two real roots."<<endl;
        cout<<"x1= "<<x1<<endl;
        cout<<"x2= "<<x2<<endl;

    }
    else if(determinant==0)
    {
        cout<<"The function has one real root."<<endl;
        x1=(-b + sqrt(determinant))/(2*a);
        cout<<"x1=x2= "<<x1<<endl;
    }
    else
    {
        cout<<"The function has no real root."<<endl;
    }
    return 0;
}

double Quadratic :: range (double left, double right, double inc) const
{
    double i, v;
    for(i=left; i<=right;i+=inc)
    {
        v = a*pow(i,2) + b*i + c;
        cout<<v<<" ";
    }
    return 0;

}

istream& operator>>(istream& is, Quadratic& val)
{
    is>>val.a>>val.b>>val.c;
    return is;
}

ostream& operator<<(ostream& os, const Quadratic& val)
{
    if(val.a<0)
        os<<"f(x)="<<showpos<<val.a<<"x^2 "<<val.b<<"x "<<val.c<<noshowpos<<endl;
    else
        os<<"f(x)="<<val.a<<"x^2 "<<showpos<<val.b<<"x "<<val.c<<noshowpos<<endl;

    return os;
}

int main()
{
    Quadratic coord;
    double left,right,inc;

    cout<<"Insert the value for a, b and c. Separate by pressing space bar."<<endl;
    cout<<"=> ";
    cin>>coord;

    if (coord.overload() !=1)
    {
        cout<<coord<<endl<<endl;
        cout<<"Input the range of x, starting with the left interval, right interval\nand increment to find the value of f(x) => ";
        cin>>left>>right>>inc;

        cout<<endl<<"The f(x) for "<<left<<"<x<"<<right<<" by increment of "<<inc<<" are => ";
        coord.range(left,right,inc);
        cout<<endl<<endl;
        coord.root();

    }
    return 0;
}