BINARY FILES
If you’re
storing a large amount of numerical data it’s more efficient to use binary I/O,
in which numbers are stored as they are in the computer’s RAM memory, rather
than as strings of characters.
We use two
new functions: write(), a member of ofstream;
and read(), a member of ifstream.
These functions think about data in terms of bytes (type char).
They don’t
care how the data is formatted, they simply transfer a buffer full of bytes
from and to a disk file.
The parameters to write()
and read() are the
address of the data buffer and its
length.
The address must be cast, using reinterpret_cast,
to type char*, and the length is
the
length in
bytes (characters), not the number of data items in the buffer.
Program to
write on to the binary file and read the same
#include
<fstream.h>
#include
<conio.h>
#include
<stdio.h>
class student
{
int rollno;
char name[20];
float marks;
public:
void input()
{
cout<<"Enter
rollno";
cin>>rollno;
cout<<"Enter
name";
gets(name);
cout<<"Enter
marks";
cin>>marks;
}
void display()
{
cout<<rollno<<"
"<<name<<" "<<marks<<endl;}};
void WRITE()
{
student s;
ofstream
f("student.dat");
char ans='y';
do
{
s.input();
f.write((char
*)&s,sizeof(s));
cout<<"continue(y/n)?";
cin>>ans;
}
while(ans=='y'||ans=='Y');
}
void READ()
{
student s;
ifstream
f("student.dat");
while(f.read((char
*)&s,sizeof(s)))
{
s.display();
}}
void main()
{
clrscr();
WRITE();
READ();
getch();}
Output
BOARD PAPER - 2015
Write a definition for function Economic() in C++ to read each record of a binary file ITEMS.DAT, find and display those items, which costs less than 2500. Assume that the file ITEMS.DAT is created with the help of objects of class ITEMS, which is defined below:
class ITEMS
{
int ID;char GIFT[20]; float Cost;
public :
void Get()
{
cin>>CODE;gets(GIFT);cin>>Cost;
}
void See()
{
cout<<ID<<":"<<GIFT<<":"<<Cost<<endl;
}
float GetCost() {return Cost;}.
};
{
ITEMS I;
ifstream fin(“ITEMS.DAT”,ios::binary);
while (fin.read((char *)&I,sizeof(I)))
{
if(I.GetCost()<2500)
I.See();
}
fin.close();
}
Find the output of the following C++ code considering that the
binary file CLIENTS.DAT exists on the hard disk with records of 100
members.
class CLIENTS
{
int Cno;char Name[20];
public :
void In(); void Out();
};
void main{)
{
fstream CF;
CF.open("CLIENTS.DAT",ios:: binary| ios::in) ;
CLIENTS C;
CF.read((char*)&C,sizeof(C));
CF.read((char*)&C,sizeof(C));
CF.read((char*)&C,sizeof(C));
int POS=CF.tellg()/sizeof(C);
cout<<"PRESENT RECORD:"<<POS<<endl;
CF.close() ;
}
PRESENT RECORD: 3
BOARD PATTERN QUESTIONS (BINARY FILES)
1)Find the output of the following
C++ code considering that the binary file CLIENTS.DAT exists on the hard disk
with a data of 200 clients :
class
CLIENTS
{
int
CCode;char CName[20];
public:
void
REGISTER(); void DISPLAY();
};
void
main()
{
fstream
File;
File.open("CLIENTS.DAT",ios::binary|ios::in);
CLIENTS
C;
File.seekg(6*sizeof(C));
File.read((char*)&C,
sizeof(C));
cout<<"Client
Number:"<<File.tellg()/sizeof(C) + 1;
File.seekg(0,ios::end);
cout<<"
of "<<File.tellg()/sizeof(C)<<endl;
File.close();
}
Ans:
Client
Number:8 of 200
2)Find
the output of the following C++ code considering that the binary file
MEM.DAT exists on the hard disk with a data of 1000 members :
class MEMBER
{
int Mcode;char
MName[20];
public:
void
Register();void Display();
};
void main()
{
fstream MFile;
MFile.open(“MEM.DAT”,
ios::binary|ios::in);
MEMBER M;
MFile.read((char*)&M,
sizeof(M));
cout<<”Rec:”<<MFile.tellg()/sizeof(M)<<endl;
MFile.read((char*)&M,
sizeof(M));
MFile.read((char*)&M,
sizeof(M));
cout<<”Rec:””<<MFile.tellg()/sizeof(M)<<endl;
MFile.close();
}
Ans:
Rec:1
Rec:3
3) Write a definition for function BUMPER() in C++ to read each
object of a binary
file GIFTS.DAT, find and display details of those gifts, which has
remarks as “ÖN
DISCOUNT”. Assume that the file GIFTS.DAT is created with the help
of objects
of class GIFTS, which is defined below :
class
GIFTS
{
int
ID;char Gift[20],Remarks[20]; float Price;
public:
void
Takeonstock()
{
cin>>ID;gets(Gift);gets(Remarks);cin>>Price;
}
void
See()
{
cout<<ID<<”:”<<Gift<<”:”<<Price<<””:”<<Remarks<<endl;
}
char
*GetRemarks() {return Remarks;}
};
Ans:
void Bumper()
{
GIFTS G;
ifstream
f("GIFTS.DAT");
int flag=0;
while(f.read((char
*)&f,sizeof(G)))
{
if
(strcmpi(G.GetRemarks(),"ON DISCOUNT")==0)
{G.See();flag=1;}
}
if(flag==0)
cout<<"Record not found";}
4) Write a definition for
function COUNTPICS( ) in C++ to read each object of a binary file PHOTOS.DAT,
find and display the total number of PHOTOS of type PORTRAIT. Assume that the
file PHOTOS.DAT is created with the help of objects of class PHOTOS, which is
defined below :
class
PHOTOS
{
int PCODE;
char PTYPE[20];//Photo Type as “PORTRAIT”,“NATURE”
public:
void ENTER()
{
cin>>PCODE;gets(PTYPE);
}
void SHOWCASE()
{
cout<<PCODE<<":"
<<PTYPE<<endl;
}
char *GETPTYPE(){return PTYPE;}};
5) Write a definition for function COUNTDEPT( ) in C++ to read
each object of a binary file TEACHERS.DAT, find and display the total number of
teachers in the department MATHS. Assume that the file TEACHERS.DAT is created
with the help of objects of class TEACHERS, which is defined below :
class
TEACHERS
{
int
TID; char DEPT[20];
public:
void
GET()
{
cin>>TID;gets(DEPT);
}
void
SHOW()
{
cout<<TID<<":"<<DEPT<<end1;
}
char
*RDEPT(){return DEPT;}};
6) Write a definition for function Economic ( ) in C++ to read
each record of a binary file ITEMS.DAT, find and display those items, which
costs less than 2500. Assume that the file ITEMS.DAT is created with the help
of objects of class ITEMS, which is defined below :
class ITEMS
{
int ID;char
GIFT[20]; float Cost;
public :
void Get()
{
cin>>CODE;gets(GIFT);cin>>Cost;
}
void See()
{
cout<<ID<<”:”<<GIFT<<”:”<<Cost<<end1;
}
float
GetCost(){return Cost;}.
};
7) Find the output of the following C++ code considering that the
binary file
CLIENTS.DAT exists on the hard disk
with records of 100 members.
class
CLIENTS
{
int
Cno;char Name[20];
public
:
void
In(); void Out();
};
void
main()
{
fstream
CF;
CF.open(“CLIENTS.DAT”,ios::binary|ios::in);
CLIENTS
C;
CF.read((char*)
&C, sizeof(C));
CF.read((char*)
&C, sizeof(C));
CF.read((char*)
&C, sizeof(C));
int
POS=CF.tellg()/sizeof(C);
cout<<”PRESENT
RECORD:”<<POS<<end1;
CF.close();
}
8) Fill in the blanks marked as
Statement 1 and Statement 2, in the program segment given below with
appropriate functions for the required task.
class
Agency
{
int
ANo; //Agent Code
char
AName[20]; //Agent Name
char
Mobile[12]; //Agent Mobile
public:
void
Enter(); //Function to enter details of agent
void
Disp(); //Function to display details of agent
int
RAno(){return ANo;}
void
UpdateMobile() //Function to update Mobile
{
cout<<²Updated Mobile:²;
gets(Mobile);
}
};
void
AgentUpdate()
{
fstream
F;
F.open(“AGENT.DAT²,ios::binary|ios::in|ios::out);
int
Updt=0;
int
UAno;
cout<<²Ano (Agent No - to update
Mobile):²;
cin>>UAno;
Agency
A;
while
(!Updt && F.read((char*)&A,sizeof(A)))
{
if
(A.RAno()==UAno)
{
//Statement
1:To call the function to Update Mobile No.
_______________________________________
;
//Statement
2:To reposition file pointer to re-write
the
updated object back in the file
_________________________________________
;
F.write((char*)&A,sizeof(A));
Updt++;
}
}
if
(Updt)
cout<<²Mobile Updated for Agent²<<UAno<<endl;
else
cout<<²Agent not in the Agency²<<endl;
F.close();
}
9) Assuming the class TOYS as
declared below, write a function in C++ to read the objects of TOYS from binary
file TOYS.DAT
and display those details of those TOYS, which are
meant for children of AgeRange ‘‘5 to 8’’.
class
TOYS
{
int
ToyCode;
char
ToyName[10];
char
AgeRange;
public:
void
Enter()
{
cin>>ToyCode;
gets(ToyName);
gets(AgeRange);
}
void
Display()
{
cout<<ToyCode<<²:²<<ToyName<<endl;
cout<<AgeRange<<endl;
}
char*
WhatAge(){return AgeRange;}
};
10) Given the binary file CAR.Dat, containing records of the following class
CAR type:
class CAR
{
int C_No;
char C_Name[20];
float Milage;
public:
void enter( ) {
cin>> C_No ; gets(C_Name) ; cin >> Milage;
}
void display( )
{
cout<< C_No ; cout<<C_Name ; cout<<
Milage;
}
int RETURN_Milage( )
{
return Milage; } };
Write a function in C++,
that would read contents from the file CAR.DAT and display the details of car
with mileage between 100 to 150.
10) Given the binary file SBAccount.dat, containing records of
the following class ACC type:
class ACC
{
int AccNo;
char Name[20];
double Balanceamt;
public:
void enter( ) { cin>> AccNo; gets(Name) ; cin >>
Balance; }
void display( )
{
cout<< AccNo; cout<< Name ; cout<< Balance; }
double RETURN_Balance( )
{
return Balance; }
};
Write a function in C++, that would
read contents from the file SBAccount.DAT and write the record contents of
those ,whose Balanceamt is more than 500000 into another binary file
“Privilege.dat” .
BOARD PATTERN QUESTIONS (TEXT FILES)
1) Write a program which uses a function CHANGE() that reads a text
file “IN.TXT” and write the contents from this file on to another file called
“OUT.TXT” with the vowels capitalized.
If “IN.TXT” contains
A creative
man is motivated by the desire to achieve, not by the desire to beat others.
“OUT.TXT” contains
A crEAtIvE
mAn Is mOtIvAtEd by thE dEsIrE tO AchIEvE, nOt by thE dEsIrE tO bEAt OthErs.
2)
Write
function definition for WORD4CHAR() in C++ to read the content of a text
file
FUN.TXT, and display all those words, which has four characters in it.
Example
:
If
the content of the file fun.TXT is as follows :
When
I was a small child, I used to play in the garden with my grand mom. Those days
were amazingly funful and I remember all the moments of that time
The
function WORD4CHAR() should display the following :
When used play with days were that time
3) Write
a function AECount() in C++, which should read each character of a text file NOTES.TXT,
should count and display the occurrence of alphabets A
and
E
(including
small cases a and e too).
Example :
If the file content is as follows :
CBSE enhanced its CCE guidelines
further.
The AECount() function should display the output as
A:1
E:7
4) Write the command to place the file
pointer at the 10th and 4th record starting position using seekp() or seekg()
command. File object is ‘file’ and record name is ‘STUDENT’.
5)
Assume
a input file stream “FILE” is opened in ios::in mode and is associated with the
file “comp.dat”, that contains records of the following structure TEST. Write a statement in C++ to position the file
pointer just before the last record
struct TEST
{ int RegNo, mark;}obj;
6)
Write
a function to count no. of character spaces and number of alphabets in a text
file “test.dat”
1) Write a program which uses a function CHANGE() that reads a text
file “IN.TXT” and write the contents from this file on to another file called
“OUT.TXT” with the vowels capitalized.
If “IN.TXT” contains
A creative
man is motivated by the desire to achieve, not by the desire to beat others.
“OUT.TXT” contains
A crEAtIvE
mAn Is mOtIvAtEd by thE dEsIrE tO AchIEvE, nOt by thE dEsIrE tO bEAt OthErs.
2)
Write
function definition for WORD4CHAR() in C++ to read the content of a text
file
FUN.TXT, and display all those words, which has four characters in it.
Example
:
If
the content of the file fun.TXT is as follows :
When
I was a small child, I used to play in the garden with my grand mom. Those days
were amazingly funful and I remember all the moments of that time
The
function WORD4CHAR() should display the following :
When used play with days were that time
3) Write
a function AECount() in C++, which should read each character of a text file NOTES.TXT,
should count and display the occurrence of alphabets A
and
E
(including
small cases a and e too).
Example :
If the file content is as follows :
CBSE enhanced its CCE guidelines
further.
The AECount() function should display the output as
A:1
E:7
4) Write the command to place the file
pointer at the 10th and 4th record starting position using seekp() or seekg()
command. File object is ‘file’ and record name is ‘STUDENT’.
5)
Assume
a input file stream “FILE” is opened in ios::in mode and is associated with the
file “comp.dat”, that contains records of the following structure TEST. Write a statement in C++ to position the file
pointer just before the last record
struct TEST
{ int RegNo, mark;}obj;
6)
Write
a function to count no. of character spaces and number of alphabets in a text
file “test.dat”
PRACTICAL BASED QUESTIONS (BINARY FILES)
EXERCISES IN BINARY FILES
1) Create
a binary file with objects of the class APPLE with the following
specifications:
Product Name – string of 25 characters
Price – float
Public member functions:
void
Enter() – to enter details
void Display() – to display details.
float RET_PRICE() – returns the price
Write following non-member functions :
CREATE() – to call the member function Enter() and write the objects on to the
binary file.
PRINT() – to read the file and print the details of all the products the products which are priced between 30000 and 40000 (inclusive) from the file by calling the member function Display()
.
Enter
the following data:
Product
|
Price
|
iPhone 6Plus
|
40999
|
iPhone SEGold
|
35399
|
iPhone 5S
|
30000
|
iPhone6
|
39300
|
3)Complete the definition of the following class.
class customer
{
int custid;
char custname[24];
float amount;
public:
void enter();// enter the
customer details
void print();// print the
customer details
int ret_custid();// return
custid
};
Write a menu driven program which accepts an option from the user
(1-Append , 2- Display, 3- Search, 4 – Exit) and implements these options
through non-member functions Append(), Display(), Search() continuously as long
as the user does not press the option 4.
·
Append() – will invoke the member function enter() and appends the
records in the binary file customer.dat.
·
Display() – will read the records from the binary file
customer.dat and invokes the print() function.
·
Search()-will input customer_id from the user and read the records
from the binary file customer.dat , searches for the existence of the
customer_id in the file, If found, invokes the print() function , otherwise
displays the error message “Not found”.
·
Exit – returns to the program
4) Complete
the definition of the following class.
class lab
{
int rollno;
int no_of_experiments;
float marks;
public:
void enter();// enter the lab
details
void print();// print the lab
details
void update(int x)
{marks = marks + x;}
int ret_no_of_exp();//
return no_of_experiments
};
Write a menu driven program which accepts an option from the user
(1-Append, 2-Modify, 3-Display, 4 – Exit) and implements these options through
non-member functions Append(), Modify(), Display() continuously as long as the
user does not press the option 4.
·
Append() – will invoke the member function enter() and appends the
records in the binary file lab.dat.
·
Modify() – will read the records from the binary file lab.dat
and invokes the update() function that
receives the additional marks as parameter. It adds 5 marks for those students
whose no_of_experiments is 15 and above, otherwise 2 marks is added.
ret_no_of_exp() function is invoked to return the no_of_experiments.
·
Display()- will read the records from the binary file lab.dat ,
prints all the records by invoking the print() function
·
Exit – returns to the program
5) Complete
the definition of the following class.
class student
{
int rollno;
char name[25];
int Class,year;
char sec;
char admn_no[15];
public:
void enter();// enter the student
details
void print();// print the student
details
int ret_year();// return year
int ret_Class();// returns
Class
};
Write a menu driven
program which accepts an option from the user (1-Append
2-Delete, 3-Display, 4 – Exit) and implements these options
through non-member functions
Append(), Delete(), Display() continuously as long as the user does not press
the option 4.
·
App () – will invoke the member function enter() and appends the
records in the binary file student.dat.
·
Del() – will read the records from the binary file student.dat and
deletes Class 12 student records belonging to the year 2015.
·
Disp()- will read the records from the binary file student.dat , prints all the
records by invoking the print() function
·
Exit – returns to the program
