File Structure ( FS ) Lab Program 6 ( 6th Semester Information Science)

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Program 6 : Write a C++ program to implement index on secondary key, the name, for a file of student objects. Implement add ( ), search ( ), delete ( ) using the secondary index

#include<iostream.h>
#include<string.h>
#include<fstream.h>
#include<stdlib.h>

//using namespace std;

class record
{
public: char age[5];
char usn[20],name[20],branch[5]; char sem[2];
}rec[20],found[20];

char st_no[5],rt_name[20];
int no;

void sort_records()
{
int i,j;
record temp;
for(i=0;i<no-1;i++)
for(j=0;j<no-i-1;j++)
if(strcmp(rec[j].name, rec[j+1].name) > 0)
{
temp=rec[j];
rec[j]=rec[j+1];
rec[j+1]=temp;
}
}

void create_indexfile()
{
fstream index,index2;
int i;
index.open(“secindex.txt”,ios::out);
index2.open(“record.txt”,ios::out);
for(i=0;i<no;i++)
{
index<<rec[i].name<<“|”
<<rec[i].usn<<“|”<<i<<“n”;
index2<<i<<“|”<<rec[i].usn<<“|”<<rec[i].name<<“|”<<rec[i].age<<“|”
<<rec[i].sem<<“|”<<rec[i].branch<<“n”;
}
}

void retrieve_record(char* index)
{
fstream file;
int i;
char ind[2],usn[20],name[20],age[3],sem[3],branch[10];
file.open(“record.txt”,ios::in);
for(i=0;i<no;i++)
{
file.getline(ind,4,’|’);
file.getline(usn,20,’|’);
file.getline(name,20,’|’);
file.getline(age,4,’|’);
file.getline(sem,4,’|’);
file.getline(branch,5,’n’);
if(strcmp(index,ind) == 0)
cout<<“nUSN: “<<usn
<<“nName: “<<name
<<“nAge: “<<age
<<“nSem: “<<sem
<<“nBranch: “<<branch;
}
file.close();
return;
}

void retrieve_details()
{
int k=0,i;
char name[20],usn[20],ind[2];
char chusn[20];
char index[20][20];
fstream file;
file.open(“secindex.txt”,ios::in);
for(i=0;i<no;i++)
{
file.getline(name,20,’|’);
file.getline(usn,20,’|’);
file.getline(ind,4,’n’);
if(strcmp(name,rt_name) == 0)
{
strcpy(found[k].name,name);
strcpy(found[k].usn,usn);
strcpy(index[k],ind);
k++;
}
}
file.close();
if(k==1)
{
retrieve_record(index[0]);
return;
}
else
{
cout<<“Please choose the candidate’s USN: n”;
for(i=0;i<k;i++)
cout<<“Name: “<<found[i].name<<” USN: “<<found[i].usn<<endl;
}
cin>>chusn;
for(i=0;i<k;i++)
{
if(strcmp(chusn,found[i].usn) == 0)
{
retrieve_record(index[i]);
return;
}
}
cout<<“Invalid Entry! n”;
return;
}

void delete_record(char indx[])
{
int i;
fstream file1,file2;
char age[5],sem[5],branch[5],usn[20],name[20],ind[5];
char index[20][20];
file2.open(“record.txt”,ios::in);
for(i=0;i<no;i++)
{
file2.getline(ind,4,’|’);
file2.getline(usn,20,’|’);
file2.getline(name,20,’|’);
file2.getline(age,5,’|’);
file2.getline(sem,5,’|’);
file2.getline(branch,8,’n’);
strcpy(index[i],ind);
strcpy(rec[i].usn,usn);
strcpy(rec[i].name,name);
strcpy(rec[i].age,age);
strcpy(rec[i].sem,sem);
strcpy(rec[i].branch,branch);
}
int flag=-1;
for(i=0;i<no;i++)
{
if(strcmp(index[i],indx) == 0)
flag=i;
}
if(flag==-1)
{
cout<<“Error!n”;
return;
}
if(flag==(no-1))
{
no–;
cout<<“Deleted!n”;
return;
}
for(i=flag;i<no;i++)
{
rec[i]=rec[i+1];
}
no–;
cout<<“Deleted!n”;
file2.close();
file1.open(“secindex.txt”,ios::out);
file2.open(“record.txt”,ios::out);
for(i=0;i<no;i++)
{
file1<<rec[i].name<<“|”<<rec[i].usn<<“|”<<i<<“n”;

file2<<i<<“|”<<rec[i].usn<<“|”<<rec[i].name<<“|”
<<rec[i].age<<“|”<<rec[i].sem<<“|”<<rec[i].branch<<“n”;
}
file1.close();
file2.close();
return;
}

void delete_index(char* nam)
{
fstream file;
int i;
int k=0;
char name[20],usn[20],ind[5],index[20][20],chusn[20];
file.open(“secindex.txt”,ios::in);
for(i=0;i<no;i++)
{
file.getline(name,20,’|’);
file.getline(usn,20,’|’);
file.getline(ind,4,’n’);
if(strcmp(nam,name)==0)
{
strcpy(found[k].name,name);
strcpy(found[k].usn,usn);
strcpy(index[k],ind);
k++;
}
}
file.close();
if(k==1)
{
delete_record(index[0]);
return;
}
else
{
cout<<“Please choose the candidate’s USN: n”;
for(i=0;i<k;i++)
{
cout<<“Name: “<<found[i].name<<” USN: “<<found[i].usn<<endl;
}
}
cin>>chusn;
for(i=0;i<k;i++)
{
if(strcmp(chusn,found[i].usn)==0)
{
delete_record(index[i]);
return;
}
}
cout<<“Invalid Entry!n”;
return;
}

int main()
{
fstream file1,file2;
int ch;
char rt_usn[20],st_name[20],st_usn[20];
char ind[2],name[20],age[2],sem[5],branch[5];
int i,flag,flag1;
file1.open(“index.txt”,ios::out);
file2.open(“record.txt”,ios::out);
if(!file1 || !file2)
{
cout<<“File creation Error!n”;
exit(0);
}
for(;;)
{
cout<<“nl:Add Recordn 2:Search Record”
<<“n3:Delete Recordn 4:Display Recordn”;
cin>>ch;
switch(ch)
{
case 1: cout<<“Enter the no. of students : “; cin>>no;
cout<<“Enter the details :n”;
for(i=0;i<no;i++)
{
cout<<“nName : “; cin>>rec[i].name;
cout<<“Age : “;    cin>>rec[i].age;
cout<<“USN : “;    cin>>rec[i].usn;
cout<<“Sem : “;    cin>>rec[i].sem;
cout<<“Branch : “; cin>>rec[i].branch;
}
sort_records();
create_indexfile();
file1.close ();
file2.close();
break;

case 2: cout<<“Enter name of the student whose record is to be displayedn”;
cin>>st_name;
file1.open(“secindex.txt”,ios::in);
if(!file1)
{
cout<<“Error !n”;
exit(0);
}
flag1=0;
for(i=0;i<no;i++)
{
file1.getline(rt_name,20,’|’);
file1.getline(rt_usn,20,’|’);
file1.getline(st_no,4,’n’);

if(strcmp(st_name,rt_name)==0)
{
retrieve_details();
flag1=1;
goto one;
}
}
one: if(!flag1)
cout<<“Record search failed !n”;
file1.close();
break;

case 3: cout<<“Enter name of student whose record is to be deletedn”;
cin>>st_name;
file1.open(“secindex.txt”,ios::in);
if(!file1)
{
cout<<“Error !n”;
exit(0);
}
flag=0;
for(i=0;i<no;i++)
{
file1.getline(rt_name,20,’|’);
file1.getline(rt_usn,20,’|’);
file1.getline(ind,4,’n’);

if(strcmp(st_name,rt_name) == 0)
{
delete_index(rt_name);
flag=1;
}
}
if(!flag)
cout<<“Deletion failed !n”;
file1.close();
break;

case 4: for(i=0;i<no;i++)
{
cout<<“nnUSN : “<<rec[i].usn
<<“nName: “<<rec[i].name
<<“nAge : “<<rec[i].age
<<“nSem : “<<rec[i].sem
<<“nBranch : “<<rec[i].branch<<“n”;
}
break;

default: cout<<“Invalid option !n”;
exit(0);
break;
}
}
return 0;
}