Program 8

BINARY FILE HANDLING - II

Write a program to display a particular record to read and modify and thus demonstrate the concept of random access in a data file.

#include<fstream.h>

#include<conio.h>

class employee

{

public:

int empno;

char name[20];

float salary;

void getdata()

{

cout<<"\n enter employee no : ";

cin>>empno;

cout<<"\n enter name : ";

cin>>name;

cout<<"\n enter salary : ";

cin>>salary;

}

void showdata()

{

cout<<empno<<"\t";

cout<<name<<"\t";

cout<<salary<<"\n";

}

};

void main()

{

employee emp;

int num;

fstream f;

f.open("empf.dat",ios::binary|ios::in|ios::out);

f.seekg(0,ios::end);

long end=f.tellg();

cout<<"\n file size : "<<end;

cout<<"\n record size :  \n "<<sizeof(emp);

int n=end/sizeof(emp);

cout<<"\n number of records : "<<n;

cout<<"\n which record do you want to modify ? ";

cin>>num;

int pos=(num-1)*sizeof(emp);

f.seekg(pos);

f.read((char*)&emp,sizeof(emp));

emp.showdata();

emp.getdata();

f.seekg(pos);

f.write((char*)&emp,sizeof(emp));

cout<<"\n record added ";

getch();

}