Heap Sort

#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( ) ; 
}