doubly simple linked list

[Felicia123]

#include <iostream>

using namespace std;

struct node{
	int data;
	node *next;
	node *prev;
}*head,*tail;

void addNodeF( int data ){
	node *newnode = new node;
	newnode->data = data;
	newnode->next = NULL;

	node *temp;
	temp = head;

	if( temp != NULL ){
		while( temp->next != NULL ){
			temp = temp->next;
		}
		temp->next = newnode;
	}
	else{
		head = newnode;
		tail = newnode;
	}
}

void addNodeR( int data ){
	node *newnode = new node;
	newnode->data = data;
	newnode->next = NULL;

	node *temp;
	temp = tail;

	if( temp != NULL ){
		temp->next = newnode;
		newnode->prev = temp;
		temp = newnode;
	}
	else{
		tail = newnode;
		head = newnode;
	}
}

void displayForward(){

	node *temp1;
	temp1 = head;

	int c = 1 ;

	if( temp1 == NULL ){
		cout << "No data inside ! " << endl;
	}
	while( temp1 != NULL ){
		cout << "Node " << c << " : " << temp1->data << endl;
		temp1 = temp1->next;
	}
}

void displayReverse(){
	node *temp1;
	temp1 = tail;

	int c = 1 ;

	if( temp1 == NULL ){
		cout << "No data inside ! " << endl;
	}
	while( temp1 != NULL ){
		cout << "Node " << c << " : " << temp1->data << endl;
		temp1 = temp1->prev;
	}

}



int main(){

	addNodeF ( 45 );
	addNodeF ( 50 );
	addNodeF ( 55 );
	addNodeF ( 60 );
	addNodeF ( 70 );

	displayForward();
	displayReverse();

	system( "pause" );
	return 0;
}

okay. here is simple doubly singly linked list.
what i done so far
but can someone teach me how to displayReverse of my linked list?
i know something wrong or miss few line code at my

void addNodeF ( int data )

there right? can someone teach and display?

[vlad from moscow]

This function is invalid

void addNodeF( int data ){
	node *newnode = new node;
	newnode->data = data;
	newnode->next = NULL;

	node *temp;
	temp = head;

	if( temp != NULL ){
		while( temp->next != NULL ){
			temp = temp->next;
		}
		temp->next = newnode;
	}
	else{
		head = newnode;
		tail = newnode;
	}
}

A new node has un undefined value in member prev.

Also it is not clear what is the difference in algorithms between functions addNodeF and asdNodeR.

[Felicia123]

it should be like that

void addNodeF( int data ){
	node *newnode = new node;
	newnode->data = data;
	newnode->next = NULL;

	node *temp;
	temp = head;

	if( temp != NULL ){
		while( temp->next != NULL ){
			temp = temp->next;
		}
		temp->next = newnode;
	}
	else{
		head = newnode;
	}
}

for addNode into the linked list.
but then i don't know how to keep track for previous linked list.
i just now already learn the singly linked list already ..
but i know how to do in in diagram but not relaly good in program..

[vlad from moscow]

What is the difference in algorithms between functions addNodeF and asdNodeR? I am asking this question because it seems they do the same.

[vlad from moscow]

And why do not you want to define a constructor for Node? For example

struct node{
	node( int data ) : data( data ), next( 0 ), prev( 0 ) {}
	int data;
	node *next;
	node *prev;
}*head,*tail;

[Felicia123]

i just trying to add node from behind.
but that doesn't matter and just ignore it.

because i don't think constructor is neccessary at here.
can u teach me for the algo reverse based on my code?

[vlad from moscow]

How are you going to reverse the list if it is not clear how you add elements in it?

[Felicia123]

yea that's why.
that's why dad node from reverse just ignore it.
will try later after i know and understand fully..

becaus ei see some reference but i get it fail.
hope to get understand from my on..

mind teach reverse?

[vlad from moscow]

Your function displayReverse is correct except that variable c is not being changed.

[Felicia123]

function is right.
but i cannot show it.
because i didnt not assign my tail to the previous linked list.

this the problem when i run.
error msg come out..

how>

[vlad from moscow]

I said you that your functiions of adding elements are incorrect but you said that it is not important.:)

[Felicia123]

err
u mean assign my linked list to reverse list?
sorry . i can't get what you mean just now.
now only get it ..

[Felicia123]

here is my full code

#include <iostream>

using namespace std;

struct node{
	int data;
	node *next;
	node *prev;
}*head,*tail;

void addNodeF( int data ){
	node *newnode = new node;
	newnode->data = data;
	newnode->next = NULL;

	node *temp;
	temp = head;

	if( temp != NULL ){
		while( temp->next != NULL ){
			temp = temp->next;
		}
		temp->next = newnode;
	}
	else{
		head = newnode;
	}
}


void reverse(){

	if( head == NULL ){
		cout << "No data inside ! " << endl;
	}
	else{
		node *temp = head;
		while( temp != NULL ){
			node *next = temp->next;
			temp->next = temp->prev;
			temp->prev = next;
			temp = next;
		}
		head = tail	;
	}
}

void displayForward(){

	node *temp1;
	temp1 = head;

	int c = 1 ;

	if( temp1 == NULL ){
		cout << "No data inside ! " << endl;
	}
	while( temp1 != NULL ){
		cout << "Node " << c << " : " << temp1->data << endl;
		temp1 = temp1->next;
		c++;
	}
}

void displayReverse(){
	node *temp1;
	temp1 = tail;

	int c = 1 ;

	if( temp1 == NULL ){
		cout << "No data inside ! " << endl;
	}
	while( temp1 != NULL ){
		cout << "Node " << c << " : " << temp1->data << endl;
		temp1 = temp1->prev;
		c++;
	}

}



int main(){

	addNodeF ( 45 );
	addNodeF ( 50 );
	addNodeF ( 55 );
	addNodeF ( 60 );
	addNodeF ( 70 );

	displayForward();
	reverse();
	displayReverse();

	system( "pause" );
	return 0;
}

but when i run display reverse
it show no data inside

[vlad from moscow]

As I said above function addNodeF is invalid.

[Felicia123]

okay.

i got it.
then what should i change?
at that function i didn't assign my tail position.
i should add what in my while loop there?

[vlad from moscow]

As i understand function addNodeF has to add a new element at the tail similar member function push_back of standard containers.

struct node{
	int data;
	node *next;
	node *prev;
	node( int data ) : data( data ), next( 0 ), prev( 0 ) {}

}*head,*tail;

void addNodeF( int data ){
	node *newnode = new node( data );

	if( tail != 0 ){
		newnode->prev = tail;
		tail->next = newnode;
	}
	else{
		head = newnode;
	}
	tail = newnode
}