Question

Provide a complete solution to the following problem using the C++ language
in a SINGLE file with a .cpp file extension.
READ THE ENTIRE QUESTION (AND THE EXAMPLE) CAREFULLY BEFORE DEVELOPING
YOUR SOLUTION!

Design the code for a class called Pi, which will be used to encapsulate
the value of pi stored as a string.

  (example ONLY)      "3.141592654"
                       | |_ _ _ _|
  whole number portion_|     |_ _ _ _ _fractional portion (9 digits)

The Pi class has the following publicly available features:

When a Pi object is created/instantiated, it may be passed a string
(maximum of 21 characters) that will contain a valid value of pi
(i.e. "3.141592654", or "3.14159", or "3.14", etc). The number of decimal
digits to display must be calculated by counting the number of characters
to the right of the decimal point . the string contains .

A Pi object may also be created without passing any parameters, in which
case the value of pi would be stored as "3.14", and the number of digits to
display would be 2 .

There is a function getPi that returns the value of pi as a double.

NOTE: You must convert the value of pi (stored as a string) to its equivalent
       double value .
    
      HINT: Starting with a value of 3, loop through the string starting
            at the index AFTER the . and compute the fractional portion
            by dividing by 10, 100, 1000. etc.

It is possible to use the << operator with a Pi object on the left and an
integer n on the right. This operator displays the value of the Pi string
to n decimal places. If n is greater than the number of digits in the string
value of Pi, then zero's are displayed after the digits. If n is negative,
then all of the digits in the Pi string are displayed .


(eg.) The following program would display the output shown in the // comments
      on the right side of the program (below):

int main( ) {
   Pi n1("3.141592654");
   Pi n2;
   double value;
                            // display
   n1 << -1                 // 3.141592654
   n1 << 6;                 // 3.141592
   n1 << 0;                 // 3


   n2 << 2;                 // 3.14
   n2 << 5;                 // 3.14000

   printf("n1 pi:%.5lf n2 pi:%.6lf\n", n1.getPi( ), n2.getPi( ));
                  // displays:         n1 pi: 3.14159 n2 pi: 3.140000
   return 0;
}

Answer 1

Code to paste

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

using namespace std;

class Pi{
    // Member variables
    string pi;
    int numberOfDecimal;
public:
    // default constructor
    Pi(){
        pi = "3.14";
        numberOfDecimal = 2;
    }
  
    // constructor with argument
    Pi(string value){
        pi = value;
        if(value.length() > 2){
            numberOfDecimal = value.length() - 2;
        }else{
            numberOfDecimal = 2;
        }
    }
  
    // converting pi to decimal
    double getPi(){
        string temp = "3";
      
        // pi without .
        if(numberOfDecimal > 0){
            for(int i = 2; i < pi.length();i++){
                temp += pi[i];
            }
        }
        return stod(temp) / pow(10,numberOfDecimal);
    }
  
    // display value of pi with n decimal Places
    void operator<<(int decimalPlaces) {
        if(decimalPlaces < 0){
            cout << pi << endl;
        }else if(decimalPlaces == 0){
            cout << pi[0] << endl;
        }else{
            if(decimalPlaces <= numberOfDecimal){
                cout << pi.substr(0,decimalPlaces + 2) << endl;
            }else{
                cout << pi;
                for(int i = 0; i < decimalPlaces - numberOfDecimal; i++){
                    cout << "0";
                }
                cout << endl;
            }
        }
                      
    }

};

int main()
{
    Pi n1("3.141592654");
    Pi n2;
    double value;
   // display
    n1 << -1;                 // 3.141592654
    n1 << 6;                 // 3.141592
    n1 << 0;                 // 3

    n2 << 2;                 // 3.14
    n2 << 5;                 // 3.14000

    printf("n1 pi:%.5lf n2 pi:%.6lf\n", n1.getPi(), n2.getPi());
    // displays:         n1 pi: 3.14159 n2 pi: 3.140000
    return 0;
}

Output screenshot