C++ program to implement Heap sort Algorithm

#include <iostream.h>
const int MAX = 10 ;
class array
{
private :
int arr[MAX] ;
int count ;
public :
array( ) ;
void add ( int num ) ;
void makeheap(int ) ;
void heapsort( ) ;
void display( ) ;
} ;
array :: array( )
{
count = 0 ;
for ( int i = 0 ; i < MAX ; i++ )
arr[MAX] = 0 ;
}
void array :: add ( int num )
{
if ( count < MAX )
{
arr[count] = num ;
count++ ;
}
else
cout << "\nArray is full" << endl ;
}
void array :: makeheap(int c)
{
 
for ( int i = 1 ; i < c ; i++ )
{
int val = arr[i] ;
int s = i ;
int f = ( s - 1 ) / 2 ;
while ( s > 0 && arr[f] < val )
{
arr[s] = arr[f] ;
s = f ;
f = ( s - 1 ) / 2 ;
}
arr[s] = val ;
}
}
void array :: heapsort( )
{
for ( int i = count - 1 ; i > 0 ; i-- )
{
int ivalue = arr[i] ;
arr[i] = arr[0] ;
arr[0]=ivalue;
makeheap(i);
 
}
}
void array :: display( )
{
for ( int i = 0 ; i < count ; i++ )
cout << arr[i] << "\t" ;
cout << endl ;
}
void main( )
{
array a ;
 
a.add ( 11 ) ;
a.add ( 2 ) ;
a.add ( 9 ) ;
a.add ( 13 ) ;
a.add ( 57 ) ;
a.add ( 25 ) ;
a.add ( 17 ) ;
a.add ( 1 ) ;
a.add ( 90 ) ;
a.add ( 3  ) ;
a.makeheap(10) ;
cout << "\nHeap Sort.\n" ;
cout << "\nBefore Sorting:\n"  ;
a.display( ) ;
a.heapsort( ) ;
cout << "\nAfter Sorting:\n" ;
a.display( ) ;
}