Fig. A.4. The Typing Test Screen
Major Project: Telephone Billing System
A.2
Learning Objectives
After 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 System
Telephone 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:
Table A.2. Key Coding Elements
Element 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 month’s value from integer to string.
Application Code
The 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<iostream.h> #include<fstream.h> #include<iomanip.h> #include<math.h> #include<stdio.h> #include<conio.h> #include<string.h> #include<process.h> #include<ctype.h> #include<dos.h>
/*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();
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 month’s 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<<“Supreme Telecom Pvt. Ltd.”; gotoxy(30,6); cout<<“_________________________”; gotoxy(30,8);
cout<<“‘M’anage Customer Records”; gotoxy(30,10);
cout<<“‘D’isplay list of customers”; gotoxy(30,12); cout<<“‘G’enerate Bill”; gotoxy(30,14); cout<<“‘H’elp”; gotoxy(30,16); cout<<“‘E’xit”; gotoxy(30,30);
cout<<“Enter your choice ”; ch1=getch(); ch1=toupper(ch1); switch(ch1) { case(‘D’): obj.display(); break; case(‘G’): obj.generate(); break; case(‘H’): obj.help(); break; case(‘E’): clrscr(); exit(1); case(‘M’): ch2=’A’; do { clrscr(); gotoxy(30,5); cout<<“Supreme Telecom Pvt. Ltd.”; gotoxy(30,6); cout<<“_________________________”;
gotoxy(30,8);
cout<<“‘A’dd new record”; gotoxy(30,10);
cout<<“‘M’odify existing record”; gotoxy(30,12);
cout<<“‘D’elete existing record”; gotoxy(30,14);
cout<<“‘E’xit”; gotoxy(30,30);
cout<<“Enter your choice”; ch2=getch(); ch2=toupper(ch2); switch(ch2) { case(‘A’): obj.add(); break; case(‘M’): obj.modify(); break; case(‘D’): obj.del(); break; case(‘E’): break;
} //End of inner switch-case block }while(ch2!=‘E’); //End of do-while block } //End of outer switch-case block
} //End of while block } //End of main()
/*Function for adding a new customer record*/ void account :: add()
{ char ch1; fstream fptr1; fptr1.open(“db.dat”,ios::app); if(fptr1.fail()) {
cout<<“Cannot open the db.dat file!”; getch();
return; }
clrscr(); gotoxy(30,5);
cout<<“Enter the new customer’s details..”;
while(1) {
gotoxy(30,8); cout<<“Name : ”;
gets(name); if(strlen(name)==0)
{
gotoxy(30,30); clreol();
cout<<“Name cannot be left blank!”; } else { gotoxy(30,30); clreol(); break; } } while(1) { gotoxy(30,10); cout<<“Address : ”; gets(address); if(strlen(address)==0) { gotoxy(30,30); clreol();
cout<<“Address cannot be left blank”; } else { gotoxy(30,30); clreol(); break; } } while(1) { gotoxy(30,12); cout<<“Ph. No : ”; cin>>phone_no; if(numdigits(phone_no)!=7) { gotoxy(54,12); clreol(); gotoxy(30,30); clreol();
cout<<“Phone no must be of seven digits”; } else { gotoxy(30,30); clreol(); break; } }
while(1) { gotoxy(30,14); cout<<“Acc no : ”; cin>>acc_no; if(numdigits(acc_no)!=5) { gotoxy(54,14); clreol(); gotoxy(30,30); clreol();
cout<<“Account no must be of five digits”; } else { gotoxy(30,30); clreol(); break; } } gotoxy(30,30);
cout<<“‘S’ave and Exit”; gotoxy(30,32);
cout<<“‘E’xit without saving ”; ch1=getch(); ch1=toupper(ch1); switch(ch1) { case(‘S’): fptr1.write((char *)this,sizeof(obj)); fptr1.close(); return; case(‘E’): fptr1.close(); return; } } //End of add()
/*Function for modifying a customer record*/ void account :: modify()
{ char ch; long input_no; int flag=0; fstream fptr1,fptr2; fptr1.open(“db.dat”,ios::in); if(fptr1.fail()) {
cout<<“Cannot open the db.dat file!”; getch();
return; }
fptr2.open(“dbtemp.dat”,ios::out); if(fptr2.fail())
{
cout<<“Cannot open the dbtemp.dat file!”; getch();
return; }
clrscr();
gotoxy(20,3);
cout<<“Enter the phone no whose record is to be modified: ”; cin>>input_no;
while(fptr1.read((char *)this, sizeof(obj))) { if(input_no==phone_no) { flag=1; gotoxy(20,5); cout<<“Name ”<<name; gotoxy(20,6); cout<<“Address ” << address; gotoxy(20,7); cout<<“Acc No ”<<acc_no; gotoxy(20,10);
cout<<“Modify this customer record (Y/N) ”; ch = getch();
ch=toupper(ch); if(ch==‘Y’) {
gotoxy(20,14);
cout<<“Enter the customer’s modified details..”; while(1) { gotoxy(20,16); cout<<“Name : ”; gets(name); if(strlen(name)==0) { gotoxy(30,30); clreol();
cout<<“Name cannot be left blank!”; } else { gotoxy(30,30); clreol(); break; } }
while(1) { gotoxy(20,18); cout<<“Address : ”; gets(address); if(strlen(address)==0) { gotoxy(30,30); clreol();
cout<<“Address cannot be left blank”; } else { gotoxy(30,30); clreol(); break; } } while(1) { gotoxy(20,20); cout<<“Ph. No : ”; cin>>phone_no; if(numdigits(phone_no)!=7) { gotoxy(44,20); clreol(); gotoxy(30,30); clreol();
cout<<“Phone no must be of seven digits”; } else { gotoxy(30,30); clreol(); break; } } while(1) { gotoxy(20,22); cout<<“Acc no : ”; cin>>acc_no; if(numdigits(acc_no)!=5) { gotoxy(44,22); clreol(); gotoxy(30,30); clreol();
cout<<“Account no must be of five digits”; }
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<<“Record for telephone number ”<<input_no<<“ does not exist”; getch(); return; } else { gotoxy(20,30);
cout<<“Customer record modified and updated successfully”; getch(); } fptr1.open(“db.dat”,ios::out); fptr2.open(“dbtemp.dat”,ios::in); while(fptr2.read((char *)this,sizeof(obj))) fptr1.write((char *)this,sizeof(obj)); fptr1.close(); fptr2.close(); } //End of modify()
/*Function for deleting a customer record*/ void account :: del()
{ char ch; long input_no; int flag=0; fstream fptr1,fptr2; fptr1.open(“db.dat”,ios::in); if(fptr1.fail()) {
getch(); return; } fptr2.open(“dbtemp.dat”,ios::out); if(fptr2.fail()) {
cout<<“Cannot open the dbtemp.dat file!”; getch();
return; }
clrscr(); gotoxy(20,3);
cout<<“Enter phone no whose record is to be deleted: ”; cin>>input_no; while(fptr1.read((char *)this,sizeof(obj))) { if(input_no==phone_no) { flag=1; gotoxy(20,5); cout<<“Name ”<<name; gotoxy(20,6); cout<<“Address ” <<address; gotoxy(20,7); cout<<“Acc No ”<<acc_no; gotoxy(20,10);
cout<<“Delete this customer record (Y/N) ”; ch=getch(); ch=toupper(ch); if(ch==‘N’) fptr2.write((char *)this,sizeof(obj)); } else fptr2.write((char *)this,sizeof(obj)); } fptr1.close(); fptr2.close(); if(ch==‘N’) return; if(flag==0) { gotoxy(20,5);
cout<<“Record for telephone number ”<<input_no<<“ does not exist”;
getch(); return; }
else {
gotoxy(20,12);
cout<<“Customer record for ”<<input_no<<“ deleted successfully”; getch(); } fptr1.open(“db.dat”,ios::out); fptr2.open(“dbtemp.dat”,ios::in); while(fptr2.read((char *)this,sizeof(obj))) fptr1.write((char *) this,sizeof(obj)); fptr1.close(); fptr2.close(); } //End of del()
/*Function for displaying customer records*/ void account :: display()
{ fstream fptr1; int count; fptr1.open(“db.dat”,ios::in); if(fptr1.fail()) {
cout<<“Cannot open the db.dat file!”; getch(); return; } clrscr(); gotoxy(2,2); cout<<“Name”; gotoxy(2,3); cout<<“____”; gotoxy(30,2); cout<<“Phone No”; gotoxy(30,3); cout<<“_________”; gotoxy(55,2); cout<<“Account Number”; gotoxy(55,3); cout<<“______________”; count=4; while(fptr1.read((char *)this,sizeof(obj))) { if(count>=19) { gotoxy(30,30);
cout<<“Press any key to continue”; getch(); clrscr(); gotoxy(2,2); cout<<“Name”; gotoxy(2,3); cout<<“____”; gotoxy(30,2); cout<<“Phone No”; gotoxy(30,3); cout<<“_________”; gotoxy(55,2); cout<<“Account Number”; gotoxy(55,3); cout<<“______________”; count=4; } gotoxy(2,count); cout<<name; gotoxy(30,count); cout<<phone_no; gotoxy(60,count); cout<<acc_no; count++; } gotoxy(22,30);
cout<<“Press any key to go back the previous menu ”; getch();
fptr1.close(); } //End of display()
/*Function for generating telephone bill*/ void account :: generate()
{ long input_no; char choice; int flag=0; int lcalls,tcalls,icalls; float bill,tbill; float rental=145.82; int dd,mm,yy;
struct date dat; getdate(&dat); dd=dat.da_day; mm=dat.da_mon; yy=dat.da_year; fstream fptr1; fptr1.open(“db.dat”,ios::in); if(fptr1.fail())
{
cout<<“Cannot open the db.dat file!”; getch();
return; }
clrscr(); gotoxy(2,2);
cout<<“Enter the telephone number: ”; cin>>input_no; flag=0; while(fptr1.read((char *)this,sizeof(obj))) { if(flag==1) break; if(phone_no==input_no) { clrscr(); gotoxy(30,2); cout<<“Supreme Telecom Pvt. Ltd.”; gotoxy(2,5); cout<<“Name : ”<<name; gotoxy(40,5); cout<<“Address : ”<<address; gotoxy(2,7);
cout<<“Account No. : ”<<acc_no; gotoxy(40,7);
cout<<“Telephone No. : ”<<phone_no;
gotoxy(2,9);
cout<<“Bill No. : ”<<mm<<“_”<<bil_ctr; bil_ctr++;
gotoxy(40,9);
cout<<“Billing Cycle : ”<<mon(mm);
gotoxy(2,16);
cout<<“Number of local Calls: ”; gotoxy(65,16);
cin>>lcalls;
gotoxy(2,18);
cout<<“Number of trunk Calls: ”; gotoxy(65,18);
cin>>tcalls;
gotoxy(2,20);
cout<<“Number of ISD Calls: ”; gotoxy(65,20);
bill=lcalls*0.25+tcalls*1.00+icalls*5.00;
gotoxy(2,32);
cout<<“Total Call Charges : ”; gotoxy(65,32); cout<<setprecision(2); cout<<bill; gotoxy(2,33); cout<<“Monthly Charges : ”; gotoxy(65,33); cout<<rental; gotoxy(2,34); cout<<“Service tax (12.36%) : ”; gotoxy(65,34); cout<<(bill+rental)*0.1236; tbill=bill+rental+(bill+rental)*0.1236; gotoxy(2,36);
cout<<“Total charges before ”<<dd<<“ ”<<mon(mm)<<“ ”<<yy;
gotoxy(65,36); cout<<tbill;
gotoxy(2,37);
cout<<“Total charges after ”<<dd<<“ ”<<mon(mm)<<“ ”<<yy;
gotoxy(65,37); cout<<tbill+100.00;
gotoxy(55,45);
cout<<“Press any Key to continue”; getch(); flag=1; } } if(flag==0) { gotoxy(2,4);
cout<<“Record for telephone number ”<<input_no<<“ does not exist”;
getch(); }
fptr1.close(); } //End of generate()
/*Function for displaying help documentation*/ void account :: help()
{
gotoxy(1,2);
cout<<“Telephone Billing System is a command-driven application that helps manage”;
gotoxy(1,4);
cout<<“records of the customers as well as generate their telephone bills. ”;
gotoxy(1,8);
cout<<“Press any key to continue...”; getch(); gotoxy(1,8); clreol(); gotoxy(15,8); cout<<“Option”; gotoxy(15,9); cout<<“______”; gotoxy(55,8); cout<<“Description”; gotoxy(55,9); cout<<“___________”; gotoxy(1,10);
cout<<“‘M’anage Customer Records -”;
gotoxy(40,10);
cout<<“Helps to manipulate customer records”; gotoxy(1,12);
cout<<“ ‘A’dd new record -”; gotoxy(40,12);
cout<<“Adds a new customer record”;
gotoxy(1,14);
cout<<“ ‘M’odify existing record -”; gotoxy(40,14);
cout<<“Modifies an existing customer record”; gotoxy(1,16);
cout<<“ ‘D’elete existing record -”; gotoxy(40,16);
cout<<“Deletes an existing customer record”;
gotoxy(1,18);
cout<<“‘D’isplay list of customers -”; gotoxy(40,18);
cout<<“Displays the list of existing customers”;
gotoxy(1,20);
cout<<“‘G’enerate Bill -”; gotoxy(40,20);
cout<<“Helps to generate a telephone bill”;
gotoxy(1,22);
gotoxy(40,22);
cout<<“Provides help documentation”;
gotoxy(1,24);
cout<<“‘E’xit -”; gotoxy(40,24);
cout<<“Exits the current screen/application”;
gotoxy(45,45);
cout<<“Press any key to go back..”; getch();
} //End of help()
Application Output
The following is a series of screenshots depicting how the Telephone Billing System application functions.
Fig. A.6. The Manage Customer Records Screen
Fig. A.8. Adding Customer Records
Fig. A.10. Deleting Customer Records
