BUBBLE SORT

`/*

* Written By: Saurabh Tiwari

* Date: 11th May 2006

*
* Sorts a binary file using a Random Access External Sort. Uses the

* BUBBLE SORT algorithm (a simplified version of the SHELL SORT algorithm)

* to swap records in the file

*

*/



#include // includes



class person_rec

{

friend class

donor_class;

private:

int id;

char name[20];

float fund;

};



class donor_class

{

private:

long num_of_rec;



public:

donor_class();

void bubble_sort();

void display();

};



//-----------------------------------------------------------------------



void main (void)

{

donor_class donor;

cout << "This is the file before sorting...\n\n";

donor.display();

donor.bubble_sort();

cout << "\nThis is the file after sorting...\n\n";

donor.display();

} // main



//-----------------------------------------------------------------------



donor_class::donor_class ()

{

person_rec rec;

fstream bifile ("a:\\a57h3g4.dat", ios::in | ios::binary);

bifile.seekg (0L, ios::end);

num_of_rec = bifile.tellg()/sizeof (rec);

cout << num_of_rec;

bifile.close();

} // constructor



//-----------------------------------------------------------------------



void donor_class::bubble_sort()

// swaps records into increasing order in a binary file

{

int i, not_sorted;

person_rec person1, person2, rec;

fstream bifile ("a:\\a57h3g4.dat", ios::in | ios::out | ios::binary);



do

{

not_sorted = 0;

for (i = 0; i < num_of_rec - 1; i = i + 1)

{

bifile.seekg ((i*sizeof(rec)), ios::beg);

bifile.read ((char *) &person1, sizeof (rec));

bifile.seekg (((i+1)*sizeof(rec)), ios::beg);

bifile.read ((char *) &person2, sizeof (rec));

if (person1.id > person2.id)

{

bifile.seekp ((i*sizeof(rec)), ios::beg);

bifile.write ((char *) &person2, sizeof (rec));

bifile.seekp (((i+1)*sizeof(rec)), ios::beg);

bifile.write ((char *) &person1, sizeof (rec));

not_sorted = 1;

} // if

} // for

}

while (not_sorted);



bifile.close();

} // bubble_sort



//-----------------------------------------------------------------------



void donor_class::display ()

// displays the file to the screen

{

person_rec person;



fstream infile ("a:\\a57h3g4.dat", ios::in | ios::binary);



while (infile.read((char *) &person, sizeof(person)))

{

cout << "ID: " << person.id << " Name: " << person.name;

cout << " Amount: $" << person.fund << endl;

} // while



infile.close();

} // display