Aim: Gain experience developing programs using STL containers and inheritance. On completion you should know how to: Write C++ code using STL container class objects. Use inheritance to facilitate programming with objects. Gain experience writing and debugging O-O programs incrementally. Prerequisites: This assignment involves writing a program to handle the billing of electricity, gas and phone accounts of a meter reading and billing company. Meter reading information on electricity, gas and phone usage is contained in the file usage.txt. Each record begins with the service type (i.e. elect, gas or phone) followed with customer details:

This information is used to calculate the customers next bill. The processing of the billing records is complicated because some suppliers offer their customers discounts if they subscribe to more than one service from them. To solve this problem you are to use object oriented programming with inheritance to represent the different types of billing records. Polymorphism will also be used to allow all records to be processed efficiently in the one array. Billing System Design The system is comprised of a BillSystem class object that own a vector of BillRecord objects in implemented in appropriately named files. The BillRecord class is a base class that has 3 derived classes for representing the 3 types of bills (elect. gas & phone). The BillSystem has public functions for reading the data file into the BillRecord vector, processing the billing information and displaying the records on the screen. Some of the functions of the BillRecord class are overridden to handle the different types of data in the derived classes. Step 1 For step 1, get the BillRecord base class working. Examine the incomplete code in the provided files and complete the function definitions of class BillRecord and BillSystem so that the customer details (only) are read into each BillRecord of the vector BRecs from usage.txt. Then test that main() displays the first 10 customer details on the screen, as shown below. Note: dont forget to delete the pointers in vector BRecs in the BillSystem destructor. # Service Supplier Customer Address AccBal Days 1 Phone Origin George Carter 24 Dingo St Exeter SA 27.49 28 2 Gas EA Paul Scott 21 Beach Rd Barham NSW 92.98 30 10 Gas EA Carol Harris 67 Broke St Milton NSW 20.45 29 Step 2 Declare the derived BillRecord classes: ElectBillRecord, GasBillRecord and PhoneBillrecord in BillSystem.h. These classes inherit the base class BillRecord. Make sure you provide private data members for storing the relevant usage information shown on page 1. Change the BillRecord classs private data member: AccountBalance and DaysSinceLastReading to protected to make them available to the derived classes. Also, make functions: ReadUsageInfo() and DisplayUsageInfo() into virtual functions so that they can be overridden by the base classes. See here: https://www.geeksforgeeks.org/virtual-function-cpp/ Now provide the derived classes with their versions of functions: ReadUsageInfo() and DisplayUsageInfo() to read and display their usage information appropriately. Modify ReadFile() in BillSystem.cpp so that it reads the service type and then allocates a ElectBillRecord, GasBillRecord or PhoneBillrecord accordingly using the new operator. Then call their ReadCustDetails() and ReadUsageInfo() functions to have the data in the file read appropriately. You might have to work on the code in each ReadUsageInfo() function to get each derived class reading its file data correctly. When you complete this step run the main() again to display 5 records showing the Customer and usage info on the screen something like this:

# Service Supplier Customer Address AccBal Days 1 Phone Origin George Carter 53 Dingo St Exeter SA 27.49 28 (LCalls: 283, 0.14 DCalls: 245, 0.32 Rental: 0.44) 2 Gas EA Paul Scott 84 Beach Rd Barham NSW 92.98 30 (Readings: 14148, 14224 HV:38.40 Rate: 0.039 SuppC: 0.56) 3 Elect Alinta Brian Crowe 61 Beach Rd Hanwood WA 18.06 31 (Readings: 113144, 113568 R1: 0.28 R1Th: 535 R2: 0.30 SuppC: 0.86) Step 3 To win more customers Dodo and Alinta provide 15% and 20% discount, respectively, to all customers who subscribe to all three services from them. To deal with this add a protected data member to the BillRecord class named Discount and a public member function named SetDiscount(float d) for setting it. Also set Discount to one in the constructor. (Note: for 15% discount set Discount to 0.85. For 20% discount set Discount to 0.8.) There are various methods for finding which customers should have the discount applied. You can devise your own method if you wish but try to keep it efficient. The processing for this should be done in a public member function in the BillSystem class named CalDiscounts().. One suggestion for finding the discounted records is to use a multiset with a user defined comparison object for ordering the BillRecord pointers. The comparison object should compare the BillRecords first by name and second by address. When all Dodo or Alinta records are inserted into this multiset, customers with the same name and address will be grouped and can be accessed with multiset functions: count(), lower_bound() and upper_bound(). (E.g. erase all BillRecord pointers with a count less than 3.) Once the discount pointers are found they can be dereferenced to set the discount appropriately. Test your code by uncommenting the step-4 code in main() and print on the screen the number of discount customers Dodo and Alinta have. Step 4 Add two more public member functions to the BillSystem class named CalBills() and PrintReport(). Also add a public pure virtual function: UpdateBalance() in the BillRecord class and override this in the derived classes. UpdateBalance() should calculate the BillAmount and add this to the AccountBalance. The BillAmount is calculated as follows: Elect : C = CrntReading - PrevReading; P = SuppyCharge * DaysSinceLastReading; If (C

/********************************************************************** * main.cpp **********************************************************************/ #include #include "BillSystem.h" using namespace std; char Menu();

int main(){

BillSystem BS;

cout

if(!BS.ReadFile("usage.txt")){ cout

cout

for(int i=0; i

cout

return 0; }

/********************************************************************** * BillRecord.cpp **********************************************************************/ #include #include #include #include "BillRecord.h" using namespace std;

// ========== class BillRecord function definitions ==========

// Default constructor BillRecord::BillRecord() {

}

// Reads customer details part of record from file bool BillRecord::ReadCustDetails(ifstream &fin) { //put code here for reading the customer details part of file record only into the private data members return true; }

// Displays customer details part of record on screen void BillRecord::DisplayCustDetails() { //display customer details (only) from private data members }

// Virtual fn for reading usage info part of record from file in derived classes bool BillRecord::ReadUsageInfo(ifstream &fin) { //the code here should jusy test BillType and read (eat) the usage info from file and discard it //later we will override this fn to read usage info into the approbriate derived classes private data members return true; }

// virtual fn for displays usage info part of record in derived classes void BillRecord::DisplayUsageInfo() { // does nothing - later we will override this fn to display the appropriate billing info in the derived classes }

// ========== Derived Class function definitions ==========

// write the function definitions of the derived classes here

/********************************************************************** * BillSystem.cpp **********************************************************************/ #include #include #include "BillSystem.h" using namespace std;

// ========== class BillSystem Public Function definitions ==========

// Destructor BillSystem::~BillSystem() { //Iterate BRecs vector and delete each ptr }

// Reads data in "usage.txt" into BRecs vector bool BillSystem::ReadFile(char *fname) {

// open fname // if not found display: "File not found." and return 0 // while not eof // allocate new memory to a temp BillRecord // if(!temp.ReadCustDetails(fin))break; // if(!temp.ReadUsageInfo(fin))break; // add temp to back of BRecs vector // close file return true; }

// Returns the number of records in BRecs int BillSystem::GetNumRecs() { return BRecs.size(); }

// Displays ith record on screen void BillSystem::DisplayRec(int i) { BRecs[i]->DisplayCustDetails(); BRecs[i]->DisplayUsageInfo(); cout

// ========== class BillSystem Private Function definitions ==========

/********************************************************************** * BillSystem.h **********************************************************************/ #ifndef BILLSYS_H #define BILLSYS_H

#include #include #include "BillRecord.h" using namespace std;

class BillSystem { public: ~BillSystem(); bool ReadFile(char *fname); int GetNumRecs(); void DisplayRec(int i); // prints ith record on screen private: vector BRecs; // vector of pointers to class BillRecord };

#endif

BillingRecord Supplier's name Customer's name Customer's address Account balance Days since last readin . . and other usage information which depend on the service type: Electricitv Previous reading Current reading Rate 1 Rate 1 threshold Rate 2 Supply charge Gas Previous reading Current reading Heating value Rate Supply charge Phone Number of local calls Local call rate Long distance call time Long distance call rate Line rental<>