Question

C++ Question Polynomial Calculator (Will Rate All Answers)

Hello, this question will be divided into many parts, this is the second part. Will quickly rate your answer! Thank you.

First part is here : https://www.chegg.com/homework-help/questions-and-answers/c-question-polynomial-calculator-rate-answers-hello-question-divided-many-parts-s-first-pa-q39525382

- Scalar Polynomial Multiplication: const Polynomial operator* (const Polynomial& P, double z) The scalar multiplication P * z simply multiplies each coefficient in p with z as depicted in the following example: 0.5 (3.2x5 + 1.6x2 -3) = 1.6x5 + 0.8x2 - 1.5 Input/Output Operators: o Input operator: istream& operator>> (istream &, Polynomial&) O Output operator: ostream& operator<< (ostream &, const Polynomial&) >> reads in a string representing the polynomial. If the string is mal-formed an exception should be thrown. << prints out the polynomial string. Direct Value Access: o Subscript operator (I-value): double& operator [] (int n) o Subscript operator (r-value): double operator[] (int n) const p[n] returns the value of the n'th coefficient of the polynomial p either as l-value or as r-value. If n does not denote a valid index (i.e., n <0) an exception shall be thrown. Function Operator: O Function operator: double operator() (double x) const The function operator evaluates the polynomial at a certain value of x. E.g., consider the following polynomial p: 2.1x2 + 0.8x – 1.5. Then p(1.2) = 2.484 or p(0) = -1.5

This question has to do with operators and polynomials.

Answer 1

Program

#include<iostream>
#include <string>
#include <cstdlib>
#include<math.h>

using namespace std;

//Polynomial class
class Polynomial
{
//private members
   private:
       int *exp;
       double *coef;
       int n;
//public members
   public:
   Polynomial();
       Polynomial(string s);
       Polynomial(const Polynomial&);
       double& operator[](int n);
       double operator[](int n) const;
       double operator()(double x) const;
       friend const Polynomial operator* (const Polynomial&, double);
       friend istream& operator>>(istream&, Polynomial&);
       friend ostream& operator<<(ostream&, Polynomial&);
~Polynomial(){}
};

//default constructor
Polynomial::Polynomial()
{
n=0;
exp=NULL;
coef=NULL;
}

//constructor
Polynomial::Polynomial(string s)
{
try{
   n=1;
   for(int i=0; i<s.size(); i++)
   {
       if(s[i]=='+' || s[i]=='-')
           n++;
   }
   exp = new int[n];
   coef = new double[n];

   s.append("+");

   int j=0, k=0, l=0;
   for(int i=0; i<s.size(); i++)
   {
       if(s[i]=='x'){
           coef[k] = stod(s.substr(j,i-j));
           k++;
       }
       if(s[i]=='+' || s[i]=='-'){
           j=i;
       }
   }
   j=0;
   for(int i=0; i<s.size(); i++)
   {
   if(s[i]=='^'){
           j=i+1;
       }
       if(s[i]=='+' || s[i]=='-'){
           exp[l] = stoi(s.substr(j,i-j));
           l++;
       }
   }
}catch(...){
cout<<"Invalid polynomial"<<endl;
}
}

//copy constructor
Polynomial::Polynomial(const Polynomial& p)
{
n = p.n;
coef = new double[n];
exp = new int[n];
for(int i=0; i<n; i++)
{
coef[i] = p.coef[i];
exp[i] = p.exp[i];
}
}

//operator * overloading
const Polynomial operator* (const Polynomial& p, double z)
{   
Polynomial q;
q.n = p.n;
q.coef = new double[p.n];
q.exp = new int[p.n];
  
for(int i=0; i<p.n; i++)
{
q.coef[i] = z * p.coef[i];
q.exp[i] = p.exp[i];
}
return q;
}

//operator >> overlaoding
istream& operator>>(istream& in, Polynomial& p)
{
string s;
in>>s;

try{
   p.n=1;
   for(int i=0; i<s.size(); i++)
   {
       if(s[i]=='+' || s[i]=='-')
           p.n++;
   }
   p.exp = new int[p.n];
   p.coef = new double[p.n];

   s.append("+");

   int j=0, k=0, l=0;
   for(int i=0; i<s.size(); i++)
   {
       if(s[i]=='x'){
           p.coef[k] = stod(s.substr(j,i-j));
           k++;
       }
       if(s[i]=='+' || s[i]=='-'){
           j=i;
       }
   }
   j=0;
   for(int i=0; i<s.size(); i++)
   {
   if(s[i]=='^'){
           j=i+1;
       }
       if(s[i]=='+' || s[i]=='-'){
           p.exp[l] = stoi(s.substr(j,i-j));
           l++;
       }
   }
}catch(...){
cout<<"Invalid polynomial"<<endl;
}
return in;
}

//operator << overloading
ostream& operator<<(ostream& out, Polynomial& p)
{
for(int i=0; i<p.n; i++)
{
if(i!=0 && p.coef[i]>0) out<<"+";
out<<p.coef[i]<<"x^"<<p.exp[i];
}
out<<endl;
  
return out;
}

//operator [] lvalue overlaoding
double& Polynomial::operator[](int n)
{
if(n<0) throw "invalid index";
return coef[n];
}

//operator [] rvalue overlaoding
double Polynomial::operator[](int n) const
{
if(n<0) throw "invalid index";
return coef[n];
}

//operator () overlaoding
double Polynomial::operator()(double x) const
{
double d = 0;
for(int i=0; i<n; i++)
{
d = d + coef[i]*pow(x, exp[i]);
}
return d;
}

//main function
int main()
{
   string s1 = "4.5x^8+3.4x^3-6.4x^1+3.1x^0";
   string s2 = "2.1x^2+0.8x^1-1.5x^0";

   Polynomial p1(s1);
   Polynomial p2(s2);
   Polynomial p3;

   cout<<p1;
cout<<p2;
  
double d = 2;

cout<<"After multiplication:"<<endl;
   p3 = p1 * d;
cout<<p3;
  
d = p2(1.2);
cout<<"At x=1.2, value of the polynomial is "<<d<<endl;
d = p2(0);
cout<<"At x=0, value of the polynomial is "<<d<<endl;
  
cout<<p2;
d=p2[2];
cout<<"rvalue of the 2nd coefficient value is "<<d<<endl;
p2[2]=5;
d=p2[2];
cout<<"After changing rvalue of the 2nd coefficient value is "<<d<<endl;
  
Polynomial p4;
cin>>p4;
cout<<p4;
  
   return 0;
}

Output Screen

4.5x^8+3.4x^3 - 6.4x^1+3.1x^0 2.1x^2+0.8x^1-1.5x^0 After multiplication : |9x^8+6.8x^3-12.8x^1+6.2x^0 At x-1.2, value of the polynomial is 2.484 At x-0, value of the polynomial is -1.5 2.1x^2+0.8x^1-1.5x^0 |rvalue of the 2nd coefficient value is -1.5 After changing rvalue of the 2nd coefficient value is 5 3x^2+1x^0 3x^2+1x^0

N.B.Whether you face any problem then share with me.