Thread: Linked List Problems

Your still not checking for memory errors when you use 'new'.

Code:

if (remainingMemory > MAX_MEMORY)

if Remaining_Memory is Greater Than Max_Memory then return TRUE.
Is that right?

BobCatPod::addSong() will only add a songnode to the head of the list.
It will not append a song to the list. so if you call it twice then you will have a memory leak.

Is there any way you can use std::list<>. Then all you would have to do is work with the songs. all the list management will be handled for you.

Originally Posted by cannsyl

I don't know how does std::list<> work?

its easy.

http://www.cprogramming.com/tutorial/stl/stllist.html
You will need to remove some stuff from your BobCatPod class.
like *head
struct SongNode
bool addSong (Song s);
int removeSong (Song s);

the std::list<> will handle this for you
Just remember that with a std::list you will use an Iterator to access the data stored in the list. Read the tutorial. it will explain it all

I have not yet taken a good look at this whole thread, but at a glance one advantage of Nor's suggestion is that eliminates the need to perform dynamic memory allocation yourself. The std::list doubly linked list handles that for you.

// ...I got that one right...I just don't understand how to implement these lists

Wasn't it Stroustrup who spoke of blowing off ones own leg, if careless? Start by looking up tutorials/implementations of linked lists. Post your progress/regress here. And be specific.

Originally Posted by cannsyl

ok it doesn't like

Clearly, the compiler just hates you. You are doomed and should commit ritual suicide immediately

Originally Posted by cannsyl

But Song is my class and s is an instance of Song so why doesn't this work?

Morbid jokes aside, you should always clearly state what is the error message. Just saying "it doesn't like <such and such>" is bad practice when asking for help.

>> ok it doesn't like

Why wouldn't it? It's valid C++, right?

Originally Posted by cannsyl

it says expected constructor, destructor, or type conversion before '<' token at std::list<Song> s;

Check that you have included the <list> standard header.

Originally Posted by cannsyl

I think my compiler does hate me, but suicide won't help me finish this assignment

Heh. More likely, your compiler just hates the code that you give it to compile.

This should get you started. I've started using the list for you. all you need to do is fix the logic errors and fill in the blanks.

Code:

//bobcatpod.h
#ifndef BOBCATPOD_H
#define BOBCATPOD_H
#include "song.h"
/*ADD*/ 
#include <list>

class BobCatPod
{
	private:
/*REMOVE*/
	//struct SongNode
	//{
	//	Song s;                  //value in this node
	//	SongNode *next;      //To point to the next node
	//};        
	//SongNode *head;
/*ADD*/
	std::list<Song> SongList;
	std::list<Song>::iterator Iter;
	public:
	//Constructor
	BobCatPod();
	//Destructor
	~BobCatPod();

	//Linked list operations
/*REMOVE*/
	//void appendNode (Song s);
	int addSong (Song s);
	int removeSong (Song s);
	bool isfull ();
	void showSongList ();
	int getTotalMemory();
	int getRemainingMemory();
	friend ostream& operator<<(ostream & os, Song & s);
};
#endif

Code:

//BobCatPod.cpp
#include "song.h"
#include "BobCatPod.h"		//<<<<<< forgot this
BobCatPod::BobCatPod() //Moved here from line 24 of the header file
{ 
}

BobCatPod::~BobCatPod()
{
	SongList.clear();
}

/*REMOVE*/
//void BobCatPod::appendNode (Song num){}
int BobCatPod::addSong(Song s){
	if( this->isfull() )
		return 0;
	SongList.push_back(s);
}

int BobCatPod::removeSong(Song s){

	return 0;
}
bool BobCatPod::isfull ()
{	 //logic errer here
     //if (remainingMemory > MAX_MEMORY)
     //{
     //           return true;
     //}

	return false;
}

int BobCatPod::getTotalMemory()
{
    //int totalMemory;	//???? you have not assigined anything to these.
    //int usedMemory;
    //totalMemory - usedMemory = remainingMemory
    //return remainingMemory;

	//Undeclared Identifers. 
	return 0;
}

int BobCatPod::getRemainingMemory(){
	//this should be what you have above here.
	return 0;
}

void BobCatPod::showSongList(){
	//I'm guessing this will be a console application.
	Iter = SongList.begin();
	while(Iter != SongList.end())
	{
	//TODO Write Display Code.
		std::cout << Iter->getArtist() << " "
			      << Iter->getTitle()  << std::endl;
		//Move to the next object in your list.
		Iter++;
	}
}