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C & C++ Multimedia Cyber Classroom
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C and C++ Multimedia Cyber Classroom (Prentice Hall) (1998).iso
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Ch15
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Fig15_12
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List.h
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C/C++ Source or Header
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1997-11-04
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166 lines
// Fig. 15.3: list.h
// Template List class definition
#ifndef LIST_H
#define LIST_H
#include <iostream.h>
#include <assert.h>
#include "listnd.h"
template< class NODETYPE >
class List {
public:
List(); // constructor
~List(); // destructor
void insertAtFront( const NODETYPE & );
void insertAtBack( const NODETYPE & );
bool removeFromFront( NODETYPE & );
bool removeFromBack( NODETYPE & );
bool isEmpty() const;
void print() const;
private:
ListNode< NODETYPE > *firstPtr; // pointer to first node
ListNode< NODETYPE > *lastPtr; // pointer to last node
// Utility function to allocate a new node
ListNode< NODETYPE > *getNewNode( const NODETYPE & );
};
// Default constructor
template< class NODETYPE >
List< NODETYPE >::List() : firstPtr( 0 ), lastPtr( 0 ) { }
// Destructor
template< class NODETYPE >
List< NODETYPE >::~List()
{
if ( !isEmpty() ) { // List is not empty
cout << "Destroying nodes ...\n";
ListNode< NODETYPE > *currentPtr = firstPtr, *tempPtr;
while ( currentPtr != 0 ) { // delete remaining nodes
tempPtr = currentPtr;
cout << tempPtr->data << '\n';
currentPtr = currentPtr->nextPtr;
delete tempPtr;
}
}
cout << "All nodes destroyed\n\n";
}
// Insert a node at the front of the list
template< class NODETYPE >
void List< NODETYPE >::insertAtFront( const NODETYPE &value )
{
ListNode< NODETYPE > *newPtr = getNewNode( value );
if ( isEmpty() ) // List is empty
firstPtr = lastPtr = newPtr;
else { // List is not empty
newPtr->nextPtr = firstPtr;
firstPtr = newPtr;
}
}
// Insert a node at the back of the list
template< class NODETYPE >
void List< NODETYPE >::insertAtBack( const NODETYPE &value )
{
ListNode< NODETYPE > *newPtr = getNewNode( value );
if ( isEmpty() ) // List is empty
firstPtr = lastPtr = newPtr;
else { // List is not empty
lastPtr->nextPtr = newPtr;
lastPtr = newPtr;
}
}
// Delete a node from the front of the list
template< class NODETYPE >
bool List< NODETYPE >::removeFromFront( NODETYPE &value )
{
if ( isEmpty() ) // List is empty
return false; // delete unsuccessful
else {
ListNode< NODETYPE > *tempPtr = firstPtr;
if ( firstPtr == lastPtr )
firstPtr = lastPtr = 0;
else
firstPtr = firstPtr->nextPtr;
value = tempPtr->data; // data being removed
delete tempPtr;
return true; // delete successful
}
}
// Delete a node from the back of the list
template< class NODETYPE >
bool List< NODETYPE >::removeFromBack( NODETYPE &value )
{
if ( isEmpty() )
return false; // delete unsuccessful
else {
ListNode< NODETYPE > *tempPtr = lastPtr;
if ( firstPtr == lastPtr )
firstPtr = lastPtr = 0;
else {
ListNode< NODETYPE > *currentPtr = firstPtr;
while ( currentPtr->nextPtr != lastPtr )
currentPtr = currentPtr->nextPtr;
lastPtr = currentPtr;
currentPtr->nextPtr = 0;
}
value = tempPtr->data;
delete tempPtr;
return true; // delete successful
}
}
// Is the List empty?
template< class NODETYPE >
bool List< NODETYPE >::isEmpty() const
{ return firstPtr == 0; }
// Return a pointer to a newly allocated node
template< class NODETYPE >
ListNode< NODETYPE > *List< NODETYPE >::getNewNode(
const NODETYPE &value )
{
ListNode< NODETYPE > *ptr =
new ListNode< NODETYPE >( value );
assert( ptr != 0 );
return ptr;
}
// Display the contents of the List
template< class NODETYPE >
void List< NODETYPE >::print() const
{
if ( isEmpty() ) {
cout << "The list is empty\n\n";
return;
}
ListNode< NODETYPE > *currentPtr = firstPtr;
cout << "The list is: ";
while ( currentPtr != 0 ) {
cout << currentPtr->data << ' ';
currentPtr = currentPtr->nextPtr;
}
cout << "\n\n";
}
#endif