project telephone billing system

Appendix A 459

Fig. A.4. The Typing Test Screen

Major Project: Telephone Billing SystemA.2

Learning ObjectivesAfter going through this project work, you will be able to:

Understand how command-driven applications are developed. Apply the concept of classes and objects to real world situations. Learn how file I/O operations are performed in C++ .

Telephone Billing SystemTelephone Billing System is a command-driven application that helps manage records of the customers and generate their telephone bills. Table A.2 lists the various coding elements of the application:

Balagurusamy-OOP_App-A.indd 459Balagurusamy-OOP_App-A.indd 459 4/7/2011 12:23:11 PM4/7/2011 12:23:11 PM

460 Object Oriented Programming with C++

Table A.2. Key Coding ElementsElement Description

account The account class realises the real world entity customer.obj An instantiation of the account class, obj is primarily used to work with the

data at hand and update it in the backend database file.db.dat Is the primary database file which stores all the backend data for the applica-

tion.add() This class method adds a new customer record.del() This class method deletes an existing customer record.modify() This class method modifies an existing customer record.display() This class method displays a list of existing customer records.display() This class method displays a list of existing customer records.generate() This class method generates the bill for an existing customer record.help() This class method displays help documentation to the user.numdigits() This method returns the number of digits contained in the passed integer value.mon() This method converts a months value from integer to string.

Application CodeThe application code for Telephone Billing System application is given below. It contains comments at appropriate places to help understand the coding elements better.

/*Header Files*/#include#include#include#include#include#include#include#include#include#include/*Defining account class*/class account{ char name[30]; char address[60]; long acc_no; long phone_no;

public: void add(); void modify(); void del(); void display(); void generate();

Telephone Billing System Application


Appendix A 461

void help();};

account obj;

int bil_ctr=1; //Counter variable for bill id

/*Function for counting number of digits in an integer*/int numdigits(long n){ return(log10(n)+1);}/*Function for converting a months value from integer to string*/char *mon(int m){ switch(m) { case(1): return(Jan);

case(2): return(Feb);

case(3): return(Mar);

case(4): return(Apr);

case(5): return(May);

case(6): return(Jun);

case(7): return(Jul);

case(8): return(Aug);

case(9): return(Sep);

case(10): return(Oct);

case(11): return(Nov);

case(12): return(Dec); }}



void main(){

char ch1,ch2; while(1)

{ clrscr();

gotoxy(30,5); cout

Appendix A 463

gotoxy(30,8); cout


gets(name); if(strlen(name)==0) { gotoxy(30,30); clreol(); cout

Appendix A 465

while(1) { gotoxy(30,14); coutacc_no; if(numdigits(acc_no)!=5) { gotoxy(54,14); clreol(); gotoxy(30,30); clreol(); cout


return; }

fptr2.open(dbtemp.dat,ios::out); if(fptr2.fail()) { cout

Appendix A 467

while(1) { gotoxy(20,18); cout


else { gotoxy(30,30); clreol(); break; } } } } fptr2.write((char *)this,sizeof(obj)); }fptr1.close(); fptr2.close(); if(ch==N) return;

if(flag==0) { gotoxy(20,5); clreol(); cout

Appendix A 469

getch(); return; }

fptr2.open(dbtemp.dat,ios::out); if(fptr2.fail()) { cout


else { gotoxy(20,12); cout

Appendix A 471

cout


{ cout

Appendix A 473

bill=lcalls*0.25+tcalls*1.00+icalls*5.00;

gotoxy(2,32); cout


gotoxy(1,2); cout

Appendix A 475

gotoxy(40,22); cout


Fig. A.6. The Manage Customer Records Screen

Fig. A.7. The Display Screen


Appendix A 477

Fig. A.8. Adding Customer Records

Fig. A.9. Modifying Customer Records



Fig. A.10. Deleting Customer Records

Fig. A.11. Generating Telephone Bill


Appendix A 479

Fig. A.12. The Help Screen


project telephone billing system

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