Thread: LinkedListery Goodness

This thread seems to have moved quite off-topic.

Seeing as you say there are many ways if making linked lists...could someone please just enter a simple program that will compile and show me how to use linked lists and output them.

Here's a link to the FAQ section of this site that provides all you ask for.

http://www.cprogramming.com/tutorial/lesson15.html

It seems easier to do it with classes....Kurisu's way looks like something that I understand...could someone just complete the code for me please.

The first example you were given by Kurisu is a pretty simple, but fully functional linked list. To create the list, the easiest way (IMHO) is to build it in 'reverse' order. By this, I mean, create the last/end node first.. then work your way to the front

Slightly modified version of Kurisu's first example:

Code:

struct node
{
   int value;
   node* next;
   node(node* n, int i) : next(n), value(i) {}
};

int main()
{
  node* current = NULL;

  for (int i=0; i!=10; ++i)
      current = new node(current, i);
      // Build a list in reverse
}

Since the above code has built the list backwards, by the end of the for loop, current will be a pointer to the node object at the front of the list.

declare a public member function of the linkedList class to display the data stored within the linked list

within the body of the function definition do something like this:

Code:

node * current;   //use a temporary node pointer to traverse the list
current = head;   //start at the front of the list
while(current != NULL)  //assuming there is a value associated with current
{
   cout << current->value;  //display it
   current = current->next; //now go to the next node in the the list
}

If your still looking for a simple example here is something that should compile.

1) Inserts 3 items into a linked list.
2) Displays all items to standard output.
3) Destroys linked list (frees allocated memory)

Code:

 #include <iostream>

 // THIS SECTION [1] WOULD NORMALLY GO INTO "linkedList.h"
 // #ifndef linkedList_h
 // #define linkedList_h
 
struct node
{
    int ID; 
    int phoneNum; 
    node *next; 

    // node *prev;  Used for a doubly linked list.  i.e. traverse both ways.
};

class linkedList
{
  public:
	linkedList(); 
	~linkedList(); 
	void insertItem(int ID, int phoneNum);
	void outputList(); 
	
  private:
	node *head; 

    // Can add more stuff if desired i.e.	   int numEntries;  node *lastEntry;
};

 // #endif
 // END OF SECTION [1]

 // THIS SECTION [2] WOULD NORMALLY GO INTO "linkedList.cpp"
 // #include "linkedList.h" 

linkedList::linkedList()
{
	head = NULL;
}

linkedList::~linkedList()
{
	node *iterator;

	while(head != NULL)
	{
		iterator = head;
		head = head->next;

		delete iterator;
	}
}

 void linkedList::insertItem(int ID, int phoneNum)
{
	

	if(head == NULL)
	{
		head = new node;
		head->ID = ID;
		head->phoneNum = phoneNum;
		head->next = NULL;
	}
	else
	{
		node *iterator = head;

		while(iterator->next != NULL)
		{
			iterator = iterator->next;
		}

		iterator->next = new node;
		iterator = iterator->next;
		iterator->ID = ID;
		iterator->phoneNum = phoneNum;
		iterator->next = NULL;
	}	
}

 void linkedList::outputList()
{
	node *iterator = head;

	while(iterator != NULL)
	{
		std::cout << "ID #: " << iterator->ID << "\nPhone Number: " << iterator->phoneNum << "\n\n";
		iterator = iterator->next;
	}
}

 // END OF SECTION [2]

 // THIS SECTION [3] WOULD NORMALLY GO INTO "main.cpp"
 // #include "linkedList.h" 

 int main()
{
    linkedList students;

   students.insertItem(1, 2983223);
   students.insertItem(2, 1456784);
   students.insertItem(3, 4868336);

   students.outputList();

   return 0;
} 
 // END OF SECTION [3]

Of course you can modify this for inserting items anywhere in the list; searching list; etc.

Graphical Representation of above Linked List