C++ code to Implement direct access file using different collision resolution techniques.

Code :
/* To implement Direct Access File ,Collision handling throgh linear probing with chaining and without replacement.
*/
#include <iomanip.h>
#include <iostream.h>
#include <fstream.h>
#include <conio.h>
#include <string.h>
#define SIZE 10
#define h(x) x%SIZE
struct student
{
int rollno;
char name[20];
float marks;
int status;
int link;
};
class lin_probe
{
char table[30];
fstream tab;
student rec;
public:
lin_probe(char *a);

void displayall();
void insert(student rec1);
void Delete(int rollno);
int search(int rollno);
void display(int recno)
{
int i=recno;
tab.open(table,ios::binary | ios::in | ios::nocreate);
tab.seekg(recno*sizeof(student),ios::beg);
tab.read((char*)&rec,sizeof(student));
if(rec.status==0)
{
cout<<”\n”<<i<<”) “<<rec.rollno<<” “<<rec.name<<” “<<setprecision(2)<<rec.marks;
cout<<” “<<rec.link;
}
else
cout<<”\n”<<i<<”) ***** Empty ********”;
tab.close();
}
void read(int recno)
{
tab.open(table,ios::binary | ios::in );
tab.seekg(recno*sizeof(student),ios::beg);
tab.read((char*) &rec,sizeof(student));
tab.close();
}
void write(int recno)
{
tab.open(table,ios::binary | ios::nocreate | ios::out | ios::in);
tab.seekp(recno*sizeof(student),ios::beg);
tab.write((char*)&rec,sizeof(student));
tab.close();
}
};
void lin_probe::lin_probe(char *a)
{
int i;
strcpy(table,a);
rec.status=1;rec.link=-1;
tab.open(table,ios::binary | ios::out);
tab.close();
for(i=0;i<SIZE;i++)
write(i);
}
void lin_probe::displayall()
{
int i=1,n;
cout<<”\n*********Data File*********\n”;
for(i=0;i<SIZE;i++)
display(i);
}
void lin_probe::insert(student rec1)
{
int n,i,j,start,k;
rec1.status=0;
rec1.link=-1;
start=h(rec1.rollno);
for(i=0;i<SIZE;i++)
{
j=(start+i)%SIZE;
read(j);
if(rec.status==0 && h(rec.rollno)==start)
break;
}
if(i<10)
{
while(rec.link!=-1)
{
j=rec.link;
read(j);
}
for(i=0;i<SIZE;i++)
{
k=(start+i)%SIZE;
read(k);
if(rec.status==1)
{
rec=rec1;
write(k);
read(j);
rec.link=k;
write(j);
return;
}
}
cout<<”\nTable is full “;
}
else
{
for(i=0;i<SIZE;i++)
{
k=(start+i)%SIZE;
read(k);
if(rec.status==1)
{
rec=rec1;
write(k);
return;
}
}
cout<<”\nTable is full “;
}
}
void lin_probe::Delete(int rollno)
{
student rec1;
int recno;
int i,j,start,k;
start=h(rollno);
for(i=0;i<SIZE;i++)
{
j=(start+i)%SIZE;
read(j);
if(rec.status==0 && h(rec.rollno)==start)//synonim found
break;
}
if(i<10)
{
if(rec.rollno==rollno )
{
rec.status=1;
write(j);
}
else
{
while(rec.rollno !=rollno && rec.link!=-1)
{
k=j;
j=rec.link;
read(j);
}
if(rec.rollno==rollno)
{ rec.status=1;
write(j);
int nextlink=rec.link;
read(k);
rec.link=nextlink;
write(k);
}
else
cout<<”\nElement not found”;
}
}
else
cout<<”\nRecord Not Found “;
}
int lin_probe::search(int rollno)
{
int start,i,j;
start=h(rollno);
for(i=0;i<SIZE;i++)
{
j=(start+i)%SIZE;
read(j);
if(rec.status==0 && h(rec.rollno)==start)//synonim found
break;
}
if(i<10)
{
while(rec.rollno !=rollno && rec.link!=-1)
{
j=rec.link;
read(j);
}
if(rec.rollno==rollno)
return(j);
else
return -1;
}
else
return -1;
}
void main()
{
lin_probe object(“table.txt”);
int rollno,op,recno;
student rec1;
clrscr();
do
{
cout<<”\n\n1)Print\n2)Insert\n3)Delete”;
cout<<”\n4)Search\n5)Quit”;
cout<<”\nEnter Your Choice:”;
cin>>op;
switch(op)
{
case 1: object.displayall();
break;
case 2:
cout<<”\nEnter a record to be inserted(roll no,name,marks) : “;
cin>>rec1.rollno>>rec1.name>>rec1.marks;
object.insert(rec1);
break;
case 3:
cout<<”\nEnter the roll no.:”;
cin>>rollno;
object.Delete(rollno);
break;
case 4:
cout<<”\nEnter a roll no. : “;
cin>>rollno;
recno=object.search(rollno);
if(recno>=0)
{
cout<<”\n Record No.: “<<recno;
object.display(recno);
}
else
cout<<”\nRecord Not Found “;
break;
}
}while(op!=5); }