\"C++ HW Assign Help\" The files List.h, List.cpp, and lab07.cpp have been provi
ID: 645089 • Letter: #
Question
"C++ HW Assign Help"
The files List.h, List.cpp, and lab07.cpp have been provided
with this assignment. You will only modify one file, List.cpp. Look
for the comments marking where you'll be adding your code.
Please look at the methods declared in List.h.
Do not add any other methods to this file.
Modify the method insert( ) in the file List.cpp to create a new node
with the incoming string s and then insert that node in the list object.
The list should be maintained in ascending alphabetical order at all times.
List.cpp is the only file that you should change.
Use lab07.cpp, List.cpp, and List.h to test your solution.
The main program in lab07.cpp reads a series of strings until it encounters
the string "xxx" (without quotes).
The string "xxx" is not added to the list, but it is a sentinel
value that indicates that the user does not wish to add more strings to the list.
The strings need to be added to the linked list in alphabetical order.
The main program displays the list after the method insert( ) adds a
new node to the list.
For example, the input could be:
bbb
ccc
aaa
xxx <-- this indicates that no more strings are to be added
At this point the program stops adding nodes to the list, and
displays the full list:
aaa
bbb
ccc
The main program has a second loop that reads strings that the user wishes
to remove from the list. The program displays the list after the method
remove( ) removes first the node matching the incoming string.
Once again, the string "xxx" (without quotes) terminates the loop.
For example, the input could be:
yyy
aab
bbb
ccc
aaa
xxx <-- this indicates that no more strings are to be removed
If the string does not appear in the list, as in the case of the string
"yyy" in the above example, nothing should happen. That is, the list
should not change and the program should not crash.
When the program reads string "bbb", the node containing "bbb" should be
removed from the list and the node should be deleted.
Again, "xxx" indicates the end of the input.
Important: make sure you deallocate any node you remove from the list.
Otherwise you have a memory leak!
Please
- use braces around any block
- use blocks as we did in our class examples
- indent your code as we have used indentations in our examples
- comment your code; do not over comment
HERE List CPP FILE TO MODIFY
#include "List.h"
// methods for Node
// constructor: init. a Node
Node::Node( const string &s, Node * const n, Node * const p )
{
word = s; // init. word with a copy of s
next = n; // next points to next node n
prev = p; // prev points to previous node p
if( n ) // is there a next node?
{
n->prev = this;
}
if( p ) // is there a previous node?
{
p->next = this;
}
}
// return a const ref to word
const string &Node::get_word( ) const
{
return word;
}
// return a pointer to next node
Node *Node::get_next( ) const
{
return next;
}
// return a pointer to previous node
Node *Node::get_prev( ) const
{
return prev;
}
// set and return a pointer to next node
Node *Node::set_next( Node *n )
{
next = n;
return next;
}
// set and return a pointer to previous node
Node *Node::set_prev( Node *p )
{
prev = p;
return prev;
}
// methods for List
List::List( ) // constructor: init. head and tail
{
cout << "List::List( ) ";
head = tail = 0;
}
List::~List( ) // destructor: deallocate the list
{
cout << "List::~List( ) ";
for( Node *p = head; p; )
{
Node *tmp = p; // remember current pointer
p = p->get_next( ); // advance p to the next Node
delete tmp; // deallocate tmp
cout << "deallocated " << tmp << " next is " << p << ' ';
}
}
void List::insert( const string &s )
{
"HERE IS WHERE THE MODIFIED LIST::INSERT(CONST STRING &S) FUNCTION WILL BE IMPLEMENTED"
// replace the call to push_back( s ) with your code to insert
// s in the doubly-linked list in alphabetical order
"NOTE THIS IS THE ONLY FUNCTION THAT SHOULD BE MODIFIED IN THE WHOLE CODE"
push_back( s ); // <- TO BE REPLACED WITH MODIFIED CODE.
}
void List::push_back( const string &s )
{
// n points to a new node
Node *n = new Node( s, 0, tail );
if( tail == 0 ) // tail not pointing to a node yet?
{
head = tail = n; // head and tail point to new node in the list
}
else
{ // tail->next points to new node
tail->set_next( n );
tail = n; // tail points to last node in the list
}
}
void List::push_front( const string &s )
{
// n points to a new node
Node *n = new Node( s, head, 0);
if( head == 0 ) // head not pointing to a node yet?
{
head = tail = n; // head and tail point to new node in the list
}
else
{ // head->prev points to new node
head->set_prev( n );
head = n; // head points to first node in the list
}
}
void List::remove( const string &s )
{
for( Node *p = head; p; p = p->get_next( ) )
{
if( p->get_word( ) == s )
{
Node *tmp;
tmp = p->get_prev( );
if( tmp ) // is there a prev node?
{
tmp->set_next( p->get_next( ) );
}
else // at the beginning of the list
{
head = p->get_next( );
}
tmp = p->get_next( );
if( tmp ) // is there a next node?
{
tmp->set_prev( p->get_prev( ) );
}
else // at the end of the list
{
tail = p->get_prev( );
}
delete p; // deallocate the node containing s
break; // terminate loop after finding first occurrence of s
}
}
}
ostream &operator <<( ostream &out, const List &list )
{
for( Node *p = list.head; p; p = p->get_next( ) )
{
cout << p << ' ' << setw( 8 ) << p->get_word( )
<< ' ' << "next:" << ' ' << p->get_next( ) << ' ';
}
return out;
}
Here LAB07 CPP FILE
#include "List.h"
int main( )
{
List list; // create an object list of type List
cout << "please enter a few words (xxx to terminate list): ";
string s; // s is a string object
while( cin >> s ) // read a string into s
{
if( s == "xxx" )
{
break; // terminate loop when string is equal to "xxx"
}
list.insert( s ); // add s to list in alphabetical order
cout << " list: " << list << ' ';
}
cout << " here is the list: " << list << ' ';
cout << "please enter word words to delete from the list (xxx to terminate): ";
while( cin >> s )
{
if( s == "xxx" )
{
break; // terminate loop when string is equal to "xxx"
}
list.remove( s ); // remove first node containing string s, if any
cout << " list: " << list << ' ';
}
cout << " the final list: " << list << ' ';
return 0;
}
HERE LIST H FILE
#include
#include
#include
using namespace std;
class Node
{
public:
// constructor
Node( const string &, Node * const, Node * const );
const string &get_word( ) const;// get a const reference to word
Node *get_next( ) const; // get a pointer to next node
Node *get_prev( ) const; // get a pointer to previous node
Node *set_next( Node * ); // set next pointer
Node *set_prev( Node * ); // set prev pointer
private:
string word;
Node *next; // pointer to the next node
Node *prev; // pointer to the previous node
// do not generate defautl copy ctor
Node( const Node & );
// do not generate default copy assign. oper.
const Node &operator =( const Node & );
};
class List
{
public:
List( ); // constructor
~List( ); // destructor
// push a node to the back of list
void push_back( const string & );
// push a node to the front of list
void push_front( const string & );
void insert( const string & ); // insert a node in alphabetical order
void remove( const string & ); // remove a node containing string
// output a list object
friend ostream &operator <<( ostream &, const List & );
private:
Node *head;
Node *tail;
// do not generate a default copy ctor
List( const Node & );
// do not generate default copy assign. oper.
const List &operator =( const List & );
};
Explanation / Answer
only need to changes in this function..
#include "List.h"
int main( )
{
List list; // create an object list of type List
cout << "please enter a few words (xxx to terminate list): ";
string s; // s is a string object
while( cin >> s ) // read a string into s
{
if( s == "xxx" )
{
break; // terminate loop when string is equal to "xxx"
}
list.add(s) // add s to list in alphabetical order
cout << " list: " << list << ' ';
}
cout << " here is the list: " << list << ' ';
cout << "please enter word words to delete from the list (xxx to terminate): ";
while( cin >> s )
{
if( s == "xxx" )
{
break; // terminate loop when string is equal to "xxx"
}
list.remove( s ); // remove first node containing string s, if any
cout << " list: " << list << ' ';
}
cout << " the final list: " << list << ' ';
return 0;
}
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