Prog-8

#include <iostream.h>

#include <fstream.h>

#include <string.h>

//Record specification

class record{

 public:

  char name[20];

  char usn[20];

}rec[20];

int no;

fstream file[8];

//The first 8 files

char fname[8][8]={"1.txt","2.txt","3.txt","4.txt","5.txt","6.txt","7.txt","8.txt"};

void merge_file(char* file1, char* file2, char* filename)

{

 record recrd[20];int k;

 k=0;

 fstream f1,f2;

 f1.open(file1,ios::in);    //open the first file

 f2.open(file2,ios::in);    //open the second file

 while(!f1.eof())           //Unpack and retrieve first file

 {

  f1.getline(recrd[k].name,20,'|');

  f1.getline(recrd[k++].usn,20,'\n');

 }

 while(!f2.eof())            //Unpack and retrieve second file

 {

  f2.getline(recrd[k].name,20,'|');

  f2.getline(recrd[k++].usn,20,'\n');

 }

 record temp;

 int t,y;

 for(t=0;t<k-2;t++)             //Sort the retrieved records

  for(y=0;y<k-t-2;y++)

   if(strcmp(recrd[y].name,recrd[y+1].name)>0)

   {

    temp=recrd[y];

    recrd[y]=recrd[y+1];

    recrd[y+1]=temp;

   }

 fstream temp1;

 temp1.open(filename,ios::out);   //Open the file to be packed into

 for(t=1;t<k-1;t++)               //Pack the sorted records onto the file

  temp1<<recrd[t].name<<"|"<<recrd[t].usn<<"\n";

 f1.close();f2.close();temp1.close();

 return;

}

void kwaymerge()

{

 char filename[7][20]={"11.txt","22.txt","33.txt","44.txt","111.txt","222.txt","1111.txt"};

 int i;

 int k;

 k=0;

 for(i=0;i<8;i+=2)                   //Merge and sort the 8 original files onto

 {                                   //the four files indicated {11.txt,22.txt....}

  merge_file(fname[i],fname[i+1],filename[k++]);

 }

 k=4;

 for(i=0;i<4;i+=2)                   //Merge and sort the four files onto 111.txt and 222.txt

 {

  merge_file(filename[i],filename[i+1],filename[k++]);

 }

                                     //Merge and sort the two files onto the 1111.txt file

 merge_file(filename[4],filename[5],filename[6]);

 return;

}

int main()

{

 int i;

 cout<<"Enter the no. of records : ";

 cin>>no;

 cout<<"\nEnter the details : \n";

 for(i=0;i<8;i++)                    //Create 8 files to store the split data

  file[i].open(fname[i],ios::out);

 for(i=0;i<no;i++)                   //Split and pack data onto the files

 {

  cout<<"Name  : ";

  cin>>rec[i].name;

  cout<<"USN   : ";

  cin>>rec[i].usn;

  file[i%8]<<rec[i].name<<"|"<<rec[i].usn<<"\n";

 }

 for(i=0;i<8;i++) file[i].close();

 kwaymerge();                          //Merge

 fstream result;

 result.open("1111.txt",ios::in);

 cout<<"\nSorted Records : \n";

 char name[20],usn[20];

 for(i=0;i<no;i++)                     //Unpack the sorted records and display

 {

  result.getline(name,20,'|');

  result.getline(usn,20,'\n');

  cout<<"\nName   : "<<name<<"\nUSN    : "<<usn<<"\n";

 }

 return 0;

}