LIBRARY_MANAGEMENT.cpp

#include<stdio.h>
#include<stdlib.h>
#include<iostream>
#include<fstream>
#include<string>
#include<sstream>
#include<ctime>
using namespace std;

/*------------------------- class student ----------------------*/

class student
{
string buffer,name,susn,sec,year;
string didlist[100];
    int count,addlist[100];
  public:
 
  void createindex();
  string extractdid(string);
  void sortindex();
  void insert();
  void display_student();
 
  void search(string);
  int searchindex(string);
  void remove(string);
 
  /* index list */
  void index_create();
  string did_extract(string);
  void index_sort();
}s;


/*------------------------- class book ------------------------*/


class book
{
    public:
           string bname,bauthor,pname;
           string blist[100];
           string pidlist[100];
           int count,addlist[100];
           void createindex();
           void remove(string);
           void insert();
           int searchindex(string);
           void searchindex2(string);
           void search(string);
       
           void sortindex();
           void display_b_record();
           void print();
           string extractpid(string);
           
           /* index list */
  void index_create();
  string pid_extract(string);
  void index_sort();
}b;


/*------------------------- class librarian ------------------------*/
class librarian
{
    public:
        string lid,lage,laddr,lname;
        string nidlist[100];
        int count,addlist[100];
        void createindex();
        void insert();
        void display_n_record();
        void print();
        void remove(string);
        int searchindex(string);
        void search(string);
        void sortindex();
        string extractnid(string);
        void addstudent();
        /* index list */
  void index_create();
  string nid_extract(string);
  void index_sort();
}l;



/* -------- index student --------*/
void student::index_create() {
    fstream file;
int pos;

string susn;
      count=-1;
      file.open("student.txt",ios::in);
      while(!file.eof())
{
           pos=file.tellg();
           buffer.erase();
           getline(file,buffer);
           if(buffer[0]!='*')
           {
                      if(buffer.empty())
                      break;
                      susn=did_extract(buffer);
                      didlist[++count]=susn;
                      addlist[count]=pos;
           }
     }
     file.close();
     index_sort();
     buffer.erase();
 }
 string student::did_extract(string buffer)
 {
     string susn;
     int i=0;
     susn.erase();
     while(buffer[i]!='|')
     susn+=buffer[i++];
     return susn;
 }
 void student::index_sort()
 {
     int i,j,tempadd;
     string tempid;
     for(i=0;i<=count;i++)
     {
           for(j=i+1;j<=count;j++)
           {
               if(didlist[i]>didlist[j])

                {
                      tempid=didlist[i];
         didlist[i]=didlist[j];
                      didlist[j]=tempid;
                      tempadd=addlist[i];

                      addlist[i]=addlist[j];
                      addlist[j]=tempadd;
                }
           }
     }
     
     cout<<"\n-------INDEXLIST--------\n";
     cout<<"\n ID\tINDEX";
     for(i=0;i<=count;i++)
     cout<<"\n"<<didlist[i]<<"\t"<<addlist[i]<<endl;
   
 }
 
 /*--------------index librarian ----------------*/
 
 void librarian::index_create() {
    fstream file;
int pos;
string buffer,lid;
    count=-1;
    file.open("librarian.txt",ios::in);
    while(!file.eof())
{
       pos=file.tellg();
       buffer.erase();
       getline(file,buffer);
       if(buffer[0]!='*')
       {
          if(buffer.empty())
             break;
          lid=nid_extract(buffer);
          nidlist[++count]=lid;
          addlist[count]=pos;
       }
    }
    file.close();
    index_sort();
    buffer.erase();
 }
 string librarian::nid_extract(string buffer)
 {
     string lid;
     int i=0;
     lid.erase();
     while(buffer[i]!='|')
     lid+=buffer[i++];
     return lid;
 }
 void librarian::index_sort()
 {
     int i,j,tempadd;
     string tempid;
     for(i=0;i<=count;i++)
     {
           for(j=i+1;j<=count;j++)
           {
               if(nidlist[i]>nidlist[j])

                {
                      tempid=nidlist[i];
         nidlist[i]=nidlist[j];
                      nidlist[j]=tempid;
                      tempadd=addlist[i];

                      addlist[i]=addlist[j];
                      addlist[j]=tempadd;
                }
           }
     }
     
     cout<<"\n-------INDEXLIST--------\n";
     cout<<"\n ID\tINDEX";

     for(i=0;i<=count;i++)
     cout<<"\n"<<nidlist[i]<<"\t"<<addlist[i]<<endl<<endl;

 }

 /*-----------book index -----------------*/
 void book::index_create()
{
    fstream file;
int pos;
string buffer;
    count=-1;
    file.open("book.txt",ios::in);
    while(!file.eof())
{
           pos=file.tellg();
           buffer.erase();
           getline(file,buffer);
           if(buffer[0]!='*')
           {
                      if(buffer.empty())
                      break;
                      bname=pid_extract(buffer);
                      pidlist[++count]=bname;
                      addlist[count]=pos;
           }
     }
     file.close();
     index_sort();
     buffer.erase();
 }
 
 string book::pid_extract(string buffer)
 {
     string bname;
     int i=0;
     bname.erase();
     while(buffer[i]!='|')
     bname+=buffer[i++];
     return bname;
 }
 
 void book::index_sort()
 {
     int i,j,tempadd;
     string tempusn;
     for(i=0;i<=count;i++)
     {
           for(j=i+1;j<=count;j++)
           {
               if(pidlist[i]>pidlist[j])
                {
                      tempusn=pidlist[i];
         pidlist[i]=pidlist[j];
                      pidlist[j]=tempusn;
                      tempadd=addlist[i];
                      addlist[i]=addlist[j];
                      addlist[j]=tempadd;
                }
           }
     }
     cout<<"\n------INDEXLIST-------\n";
     cout<<"\nBOOK ID\tINDEX";
     for(i=0;i<=count;i++)
     cout<<"\n"<<pidlist[i]<<"\t"<<addlist[i]<<endl;

 }


/* ---------------student starts from here----------------- */


void student::createindex() {
    fstream file;
int pos;
string susn;
      count=-1;
      file.open("student.txt",ios::in);
      while(!file.eof())
{
           pos=file.tellg();
           buffer.erase();
           getline(file,buffer);
           if(buffer[0]!='*')
           {
                      if(buffer.empty())
                      break;
                      susn=extractdid(buffer);
                      didlist[++count]=susn;
                      addlist[count]=pos;
           }
     }
     file.close();
     sortindex();
     buffer.erase();
 }
 
 void student::insert()
 {
     string susn,name,year,sec;
     int pos,h=0;
     fstream fp;

cout << "\nUsn\n";
     cin>>susn;
     cout << "\nName\n";
     cin>>name;
     cout << "\nyear\n";
     cin>>year;
     cout << "\nsection\n";
     cin>>sec;
     buffer.erase();
     buffer=susn+"|"+name+"|"+year+"|"+sec+"$\n";
     h=h+1;
     fp.open("student.txt",ios::out|ios::app);  
     pos=fp.tellp();
     fp<<buffer;
     fp.close();
     didlist[++count]=susn;
     addlist[count]=pos;
     
     sortindex();
     cout<<"\nstudent added Successfully....\n";
 }
 
 string student::extractdid(string buffer)
 {
     string susn;
     int i=0;
     susn.erase();
     while(buffer[i]!='|')
     susn+=buffer[i++];
     return susn;
 }
 
 void student::sortindex()
 {
     int i,j,tempadd;
     string tempid;
     for(i=0;i<=count;i++)
     {
           for(j=i+1;j<=count;j++)
           {
               if(didlist[i]>didlist[j])

                {
                      tempid=didlist[i];
         didlist[i]=didlist[j];
                      didlist[j]=tempid;
                      tempadd=addlist[i];

                      addlist[i]=addlist[j];
                      addlist[j]=tempadd;
                }
           }
     }
     /*
     cout<<"\n-------INDEXLIST--------\n";
     cout<<"\n ID\tINDEX";
     for(i=0;i<=count;i++)
     cout<<"\n"<<adminlist[i]<<"\t"<<addlist[i]<<endl;
    */
 }
 
 void student::search(string key)
 {
     int pos=0,t;
     fstream file;
     buffer.erase();
     pos=searchindex(key);
     if(pos==-1)
      cout<<"Record not found\n";
     else if(pos>=0)
     {
           file.open("student.txt");
           t=addlist[pos];
           file.seekp(t,ios::beg);
           getline(file,buffer);
           cout<<"Record found\n";
           cout<<"\nRecord:\n"<<buffer;
           file.close();
     }
 }
 
             
 int student::searchindex(string key)
 {
     int low=0,high=count,mid=0,flag=0;
     while(low<=high)
     {
           mid=(low+high)/2;
           if(didlist[mid]==key)
           {
                flag=1;
                break;
           }
           else if(didlist[mid]<key)
                low=mid+1;
           else if(didlist[mid]>key)
                high=mid-1;
     }
     if(flag)
           return mid;
     else
           return -1;
 }
 
 void student::remove(string key)
 {
  fstream fp;
  char delch='*';
int pos=0,i,address;
string buffer,susn,name,year,section;
fstream file;
  pos=searchindex(key);
  if(pos>=0)
  {
       file.open("student.txt");
       address=addlist[pos];
       file.seekp(address,ios::beg);
       file.put(delch);
       file.close();
       cout<<"Record has been deleted\n";
       for(i=pos;i<count;i++)
       {
       didlist[i]=didlist[i+1];
       addlist[i]=addlist[i+1];
       }
      count--;
  }  else
       cout<<"Record not found\n";
     
 }
  void student::display_student(){
     string line;
     cout<<"The student details are\n";
     fstream fp;
     fp.open("student.txt");
     while(!fp.eof())
       {
           getline(fp,line);
           cout<<line;cout<<"\n";
        }
     }
     /*system("cat student.txt");*/
     
 /*void student::print()
 {      
        ifstream fp;string line;string a[100],fp[100];int count;
        fp.open("student.txt");
        split(fp,'|');
        for(i=0;i<=count;i++)
           {
               a[i]=fp[i];
           }
         for(i=0;i<=count;i++)
           {
             cout<<a[i];
           }
        ifstream fp;string buffer;string a[100][100];
        fp.open("student.txt"); int i,h,j;
        while(fp.good())
             {
            for(i=0;i<h;i++)
                {  
                  for(j=0;j<4;j++)
                {
                    getline(fp,buffer,'|');
                    a[i][j]=buffer;i++;j++;
                }
 
                }
                }

            for(i=0;i<h;i++)
                {  
                  for(j=0;j<4;j++)
                {
                   
                     cout<<a[i][j];i++;j++;
                     cout<<"\n";
                }
 
             }
            /* for(i=0;i<=4;i++)

             {
                getline(fp,buffer,'|');
                a[i]=line;
             }
             }
             for( i=0;i<4;i++)
             {
                cout<<a[i];cout<<"\n";
             }
        cout<<"name"<<a[1];
        cout<<"section"<<a[4];
       
       
 }
*/

/*  ------------- librarian starts from here -----------*/

void librarian::createindex() {
    fstream file;
int pos;
string lid,buffer;
    count=-1;
    file.open("librarian.txt",ios::in);
    while(!file.eof())
{
       pos=file.tellg();
       buffer.erase();
       getline(file,buffer);
       if(buffer[0]!='*')
       {
          if(buffer.empty())
             break;
          lid=extractnid(buffer);
          nidlist[++count]=lid;
          addlist[count]=pos;
       }
    }
    file.close();
    sortindex();
    buffer.erase();
 }
 
 void librarian::insert()
 {
    string buffer,lname,laddr,lid,lage;
    int pos;
    fstream fp;

cout << "\nID\n";
    cin >> lid;
    cout << "\nEnter Name\n";
    cin >> lname;
    cout << "\nAge\n";
    cin >> lage;
    cout << "\nAddress\n";
    cin >> laddr;
    buffer.erase();
    buffer=lid+"|"+lname+"|"+lage+"|"+laddr+"$\n";
    fp.open("librarian.txt",ios::out|ios::app);  
    pos=fp.tellp();
    fp<<buffer;
    fp.close();
    nidlist[++count]=lid;
    addlist[count]=pos;
 
    sortindex();
    cout<<"\nlibrarian added Successfully....\n";
     
 }
 


 void librarian::addstudent()
 {
    string buffer,sname,susn,bname,date_of_issue;
    int pos;
    fstream fp;

cout << "\nStudent usn :\n";
    cin >> sname;
    cout << "\nstudent name :\n";
    cin >> susn;
    cout << "\nBook name :\n";
    cin >> bname;
    cout << "\n date of issue :\n";
    cin >> date_of_issue;
    buffer.erase();
    buffer=sname+"|"+susn+"|"+bname+"|"+date_of_issue+"$\n";
    fp.open("bookissue.txt",ios::out|ios::app);  
    pos=fp.tellp();
    fp<<buffer;
    fp.close();
  
    cout<<"\nBook issued Successfully....\n";
     
 }



 string librarian::extractnid(string buffer)
 {
     string lid;
     int i=0;
     lid.erase();
     while(buffer[i]!='|')
     lid+=buffer[i++];
     return lid;
 }
 void librarian::sortindex()
 {
     int i,j,tempadd;
     string tempid;
     for(i=0;i<=count;i++)
     {
           for(j=i+1;j<=count;j++)
           {
               if(nidlist[i]>nidlist[j])

                {
                      tempid=nidlist[i];
         nidlist[i]=nidlist[j];
                      nidlist[j]=tempid;
                      tempadd=addlist[i];

                      addlist[i]=addlist[j];
                      addlist[j]=tempadd;
                }
           }
     }
     /*
     cout<<"\n-------INDEXLIST--------\n";
     cout<<"\n ID\tINDEX";
     for(i=0;i<=count;i++)
     cout<<"\n"<<adminlist[i]<<"\t"<<addlist[i]<<endl;
*/
 }
 
 void librarian::search(string key)
 {
     int pos=0,t;
     string buffer;
     fstream file;
     buffer.erase();
     pos=searchindex(key);
     if(pos==-1)
         cout<<"Record not found\n";
     else if(pos>=0)
     {
           file.open("librarian.txt");
           t=addlist[pos];
           file.seekp(t,ios::beg);
           getline(file,buffer);
           cout<<"Record found\n";
           cout<<"\nRecord:"<<buffer;
           file.close();
     }
 }
 
 int librarian::searchindex(string key)
 {
     int low=0,high=count,mid=0,flag=0;
     while(low<=high)
     {
           mid=(low+high)/2;
           if(nidlist[mid]==key)
           {
                flag=1;
                break;
           }
           else if(nidlist[mid]<key)
                low=mid+1;
           else if(nidlist[mid]>key)
                high=mid-1;
     }
     if(flag)
           return mid;
     else
           return -1;
 }
 
 void librarian::remove(string key)
 {
  fstream fp;
  char delch='*';
int pos=0,i,address;
string buffer,lid,lname,lage,laddr;
fstream file;
  pos=searchindex(key);
  if(pos>=0)
  {
       file.open("librarian.txt");
       address=addlist[pos];
       file.seekp(address,ios::beg);
       file.put(delch);
       file.close();
       cout<<"Record has been deleted\n";
       for(i=pos;i<count;i++)
       {
       nidlist[i]=nidlist[i+1];
       addlist[i]=addlist[i+1];
       }
      count--;
  }  else
       cout<<"Record not found\n";
 
 }
  void librarian::display_n_record(){
     
     cout<<"The librarian details are\n";
     
     fstream fp;string line;
     fp.open("librarian.txt");
     while(!fp.eof())
       {
           getline(fp,line);
           cout<<line;cout<<"\n";
        }
     }

 
 void librarian::print()
 {
       
cout<<"librarian Id:"<<lid<<" librarian Name:"<<lname<<" Age: "<<lage<<" Address :"<<laddr<<endl;
 }




/*--------------------------------book -- starts from here ----------------------*/


void book::createindex()
{
    fstream file;
int pos;
string buffer,bname;
    count=-1;
    file.open("book.txt",ios::in);
    while(!file.eof())
{
           pos=file.tellg();
           buffer.erase();
           getline(file,buffer);
           if(buffer[0]!='*')
           {
                      if(buffer.empty())
                      break;
                      bname=extractpid(buffer);
                      pidlist[++count]=bname;
                      addlist[count]=pos;
           }
     }
     file.close();
     sortindex();
     buffer.erase();
 }
 
 string book::extractpid(string buffer)
 {
     string bname;
     int i=0;
     bname.erase();
     while(buffer[i]!='|')
     
   
     bname+=buffer[i++];
     return bname;
 }
 
 void book::insert()
 {
     string bname,bauthor,pname,buffer;
     int pos,j;
     fstream file;
     
     
      cout<<"Enter  book name \n";
      cin>>bname;
      cout<<"Enter  Author name \n";
      cin>>bauthor;
      cout<<"Enter  Publisher name \n";
      cin>>pname;
   
      buffer+=bname+"|"+bauthor+"|"+pname+"$"+"\n";
      file.open("book.txt",ios::out|ios::app);
      pos=file.tellp();
      file<<buffer;
      file.close();
   
      pidlist[++count]=bname;
      addlist[count]=pos;
      sortindex();
      cout<<"\nBook Registered Successfully....\n";
 }
 
 void book::sortindex()
 {
     int i,j,tempadd;
     string tempusn;
     for(i=0;i<=count;i++)
     {
           for(j=i+1;j<=count;j++)
           {
               if(pidlist[i]>pidlist[j])
                {
                      tempusn=pidlist[i];
         pidlist[i]=pidlist[j];
                      pidlist[j]=tempusn;
                      tempadd=addlist[i];
                      addlist[i]=addlist[j];
                      addlist[j]=tempadd;
                }
           }
     }
/*     cout<<"\n------INDEXLIST-------\n";
     cout<<"\nPATIENT ID\tINDEX";
     for(i=0;i<=count;i++)
     cout<<"\n"<<pidlist[i]<<"\t"<<addlist[i]<<endl;
*/
 }
  void book::search(string key)
 {
     int pos=0,t;
     string buffer;
     fstream file;
     buffer.erase();
     searchindex2(key);
   
 }

   int book::searchindex(string key)
 {
     int low=0,high=count,mid=0,flag=0;
     while(low<=high)
     {
           mid=(low+high)/2;
           if(pidlist[mid]==key)
           {
                flag=1;
                break;
           }
           else if(pidlist[mid]<key)
                low=mid+1;
           else if(pidlist[mid]>key)
                high=mid-1;
     }
     if(flag)
           return mid;
     else
           return -1;
 }


void book::searchindex2(string key)     //here we want to match the common elements present in the pidlist
 {
     int i,count,t,j;
     string buffer;
     fstream file;
     buffer.erase();
     cout<<"\nRecords details: \n";
     for(i=0;i<=count;i++)
         {
           if(pidlist[i]==key)
             {
                file.open("book.txt");
                t=addlist[i];
                file.seekp(t,ios::beg);
                getline(file,buffer);
                cout<<"\n"<<buffer;
                file.close();
             }
 
          }
 }
 
void book::remove(string key)
 {
  fstream fp;
  char delch='*';
int pos=0,i,address;

fstream file;
    pos=searchindex(key);
    if(pos>=0)
    {
       file.open("book.txt");
       address=addlist[pos];
       file.seekp(address,ios::beg);
       file.put(delch);
       file.close();
       cout<<"Record has been deleted\n";
       for(i=pos;i<count;i++)
       {
       pidlist[i]=pidlist[i+1];
       addlist[i]=addlist[i+1];
       }
      count--;
    }  
    else
       cout<<"Record not found\n";
 
 }
 
 void book::display_b_record()
 {
     
     
     cout<<"book details";
   
     
     fstream fp;string line;
     fp.open("book.txt");
     while(!fp.eof())
       {
           getline(fp,line);
           cout<<line;cout<<"\n";
        }
     }

   
 
 
void book::print()
{
cout<<"Book name:"<<bname<<" Author name"<<bauthor<<"Publisher name"<<pname<<endl;
}

/*------------------Main()----*/




 int main()
 {
     int ch;
     string key;
     book b;
     student s;
     librarian l;
     
   
     b.createindex();
     s.createindex();
     l.createindex();
   
     
     mainpage:
     
    while(1)
    {
            int sch,nch,rch;
            string username="admin",password="admin",u,p;
            cout<<"\n\t******* LIBRARY MANAGEMENT USING PRIMARY INDEX *******\n";
            cout<<"\n\t\tEnter \n\t\t1. Admin\n\t\t2. Student\n\t\t3. librarian\n\t\t0. Exit\n";
            cout<<"\nEnter your choice\n";
            cin>>ch;
            switch(ch)
            {
        case 1: cout<<"Enter your username\n";
                    cin>>u;
                    cout<<"Enter your password\n";
                    cin>>p;
                    if(u==username && p==password)
                    {
                        int ach;
                        cout<<"\nWelcome Admin\n";
                        admin:
          while(1)
          {

  cout<<"----------------------\n";
  cout<<"|   ADMIN SECTION     |\n";
  cout<<"----------------------\n";
  cout<<"\n1.student\t\t2.librarian\n3.book\t\n\n\t\t\t(0) <<-- BACK\n";  
  cout<<"\nEnter your choice\n";
  cin>>ach;
  switch(ach)
  {
  case 1: while(1)
  {
  int sch;
  cout<<"-----------------------** STUDENT **---------------------------\n";
  cout<<"\n1. Add student \t\t\t2. Display student records\n3. Remove student Record\t\t4. View index list\n\n\t\t\t(0) <<-- BACK\n";
  cout<<"--------------------------------------------------------------\n";
  cout<<"\nEnter your choice\n";
  cin>>sch;
  switch(sch)
  {
  case 1:s.insert();
               break;
        case 2:s.display_student();
               break;
        case 3:{cout<<"Enter student usn :";
               cin>>key;
               s.remove(key);
               cout<<"Updated file is :\n";
                 
              fstream fp;string line;
             fp.open("student.txt");
           while(!fp.eof())
              {
           getline(fp,line);
           cout<<line;cout<<"\n";
               }
     }
               break;
        case 4:s.index_create();
          break;
        case 0:goto admin;
            break;
        default: cout<<"Invalid choice";
  }
  }
  break;  

  case 2: while(1)
  {
  int n_ch;
  cout<<"-----------------------** LIBRARIAN **---------------------------\n";
  cout<<"\n1. Add librarian \t\t\t2. Display librarian records\n3. Remove librarian Record\t\t4. View index list\n\n\t\t\t(0) <<-- BACK\n";
  cout<<"--------------------------------------------------------------\n";
  cout<<"\nEnter your choice\n";
  cin>>n_ch;
  switch(n_ch)
  {
  case 1: l.insert();
                               
                break;
        case 2: l.display_n_record();
                break;
        case 3:{ cout<<"Enter librarian ID :";
                cin>>key;
                l.remove(key);
                cout<<"Updated file is :\n";
                 
     fstream fp;
     fp.open("librarian.txt");
     while(!fp.eof())
       {
            string line;
           getline(fp,line);
           cout<<line;cout<<"\n";
        }
     
                }break;
        case 4: l.index_create();
                        break;
          case 0: goto admin;
                        break;
          default: cout<<"Invalid choice";
  }
  }
  break;
 
  case 3: while(1)
  {
  int b_ch;
  cout<<"-----------------------** BOOK **---------------------------\n";
  cout<<"\n1. Add books \t\t\t2.Remove book Record\t\t3. Display book records\t\t4. View index list\n\n\t\t\t(0) <<-- BACK\n";
  cout<<"--------------------------------------------------------------------\n";
  cout<<"\nEnter your choice\n";
  cin>>b_ch;
  switch(b_ch)
  {      
  case 1: system("clear");
                               b.insert();
                break;
       
        case 2:{ cout<<"Enter book ID :";
                cin>>key;
                b.remove(key);
                cout<<"Updated file is :\n";
               
     fstream fp;
     fp.open("book.txt");
     while(!fp.eof())
       {
           string line;
           getline(fp,line);
           cout<<line;cout<<"\n";
        }
                }break;
                case 3: b.display_b_record();
  break;
        case 4: b.index_create();
        break;
          case 0: goto admin;
          break;
          default: cout<<"Invalid choice";
  }
  }
  break;
 
 
  case 0: goto mainpage;
  break;
  default: cout<<"Invalid choice";
  }
  }
  }
  else
     exit(0);
 

        case 2:cout<<"Welcome\n";
          cout<<"----------------------\n";
    cout<<"|   STUDENT SECTION     |\n";
    cout<<"----------------------\n";
                   cout<<"1. Search book \n2. Display book details\n\n\t\t\t(0) <<--BACK\nEnter your choice \n";
                   cout<<"------------------------\n";
                   cin>>sch;
                   switch(sch)
                   {
                      case 1: system("clear");
                              cout<<"Enter book name\n";
                              cin>>key;
                              b.search(key);
                              break;
                 case 2: b.display_b_record();
                           break;
                   case 0: goto mainpage;
                   default: cout<<"Invalid choice";        
                   }
             break;

        case 3: cout<<"Welcome librarian\n";
        cout<<"----------------------\n";
  cout<<"|   LIBRARIAN SECTION     |\n";
  cout<<"----------------------\n";
                     cout<<"1. Search student Record\n 2.Display student Record\n3. Book  issued \n 4.Display issued book\nEnter your choice\n\n\t\t\t(0) <<-- BACK\n";
                     cout<<"------------------------\n";
                     cin>>nch;
                     switch(nch)
                     {
                       case 1: system("clear");
                               cout<<"Enter student ID\n";
                               cin>>key;
                               s.search(key);
                               break;

                 case 3:l.addstudent();break;
             
                case 2: s.display_student();
                        break;
                case 4: system("cat bookissue.txt");break;
                case 0: goto mainpage;
                default: cout<<"Invalid choice";
                      }
              break;

       
         case 0:exit(0);      
         default: cout<<"Invalid Choice";
       

      }
  }
 }