Help with linked list - for google science fair

bretttheturner (10)
I have been using a linked list but when a function is supposed to return the character string it always has a runtime error and breaks because it doesn't work, the function is getData

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#ifndef CNODE_H
#define CNODE_H

class cNode{

	friend class cList;								// allow the list class access to the private data members of listNode
	friend class Brain;
																
public:

	cNode (char *info);
	char *getData();
	cNode getNextNode();


private:

	char *data;												//information included in the listNode
	cNode *nextNode;									//a pointer link to the next element of the list
	char *linkID;												//an ID for the listNode that can be checked when searching

};


cNode::cNode(char *info) : data(info), nextNode(0){

		

}


char *cNode::getData() {

	return data;	//it breaks here      WHY???????????????

}


cNode cNode::getNextNode(){

	return *nextNode;

}

#endif
m4ster r0shi (2201)
It's difficult to tell what the problem is with only that much info.
Could you show us the way you use your linked list?

Also, if you want a list of strings, you can just use std::list<std::string>
and focus on other, more important parts of your project, unless,
of course, implementing a string list is the main part of your project.

Useful links:

http://cplusplus.com/reference/string/string/
http://cplusplus.com/reference/stl/list/
Last edited on
Mophisto (2)
I have compiled your code, and it works fine. Can you paste the wrong message?
By the way, I am using gcc 4.5.0.
bretttheturner (10)
It was being used by another class, I figured out the problem, a control structure wasn't written right so it kept trying to access data that didn't exist :\ but I have a bigger problem now, after I solved the problem I presented above, I saved a copy of each of the resource files to my desktop, and my compiler flipped out Im getting 80 errors that don't make any sense


Error 25 error C2065: 'lastNode' : undeclared identifier

Error 35 error C2065: 'currentNode' : undeclared identifier

Error 40 error C2079: 'Brain::knowledgeList' uses undefined class 'kList'

when before I saved the files, everything was fine and I have included all of the right resource files...


please help
Mophisto (2)
I'm afraid that you have to paste your code, the error is obvious. You haven't include the .h files.
bretttheturner (10)
I have numerous times, nothing changed at all, I just went through the list of resource files -> save as, then after that compile, and nothing worked, nothing changed, no other code was written nothing
Last edited on
bretttheturner (10)
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#ifndef KLIST_H
#define KLIST_H

#include "kNode.h"
#include "Thing.h"

class kList{

	friend class Brain;

public:

	kList();
	~kList();
	void add(char *);						//add a node at the end of the list
	bool remove();										//remove a node from the back of the list
	bool isEmpty();
	int getLength();

private:

	kNode *firstNode;
	kNode *lastNode;
	kNode *getNewNode(char *);

};


kList::kList() : firstNode(0), lastNode(0){
	
}


kList::~kList(){

	if (!isEmpty()){

		std::cout<<"destroying all nodes in the list\n";
		kNode *currentNode = firstNode;
		kNode *tempNode;

		while (currentNode != 0){

			tempNode = currentNode;

			currentNode = currentNode->nextNode;

			delete tempNode;

		}

	}
	std::cout<<"All Nodes were destroyed\n";

}

void kList::add(char *id){

	kNode *newNode = getNewNode(id);

	if (isEmpty()){							//if the list is empty

		firstNode = lastNode = newNode;

	}
	else{									//if its not

		lastNode->nextNode = newNode;
		lastNode = newNode;

	}

}

kNode *kList::getNewNode(char *id){

	return new kNode(id);

}

bool kList::isEmpty(){

	return firstNode == 0;													//if the first pointer is = 0 (it doesnt point to anything

}

int kList::getLength(){

	kNode *currentNode = firstNode;

	if (!isEmpty()){

		for (int counter = 1; currentNode->nextNode != 0; counter++){
		
			if (currentNode = lastNode){

				return counter;

			}

		}
	}

	else{

		return 0;

	}

}

#endif



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#ifndef KNODE_H
#define KNODE_H

#include "Thing.h"
#include "kList.h"
#include <string>
using namespace std;

class kNode{

	friend class kList;
	friend class Brain;

public:

	kNode(char *);
	char *getPropertiesListNode();				//returns the first pointer from the proporties list
	char *getId();								//returns the ID of the Node (contains the thing class)
	void addProperty(char *);
	void setId(char *);
	bool propertyExist( char *);
	void addOperator(char *);

private:

	Thing Data;
	kNode *firstNode;
	kNode *nextNode;

};

kNode::kNode(char *id) : firstNode(0), nextNode(0){
	
	Data.setId(id);							//creates a new thing object so with the ID and proporties that are passed through the function

}

char *kNode::getId() {

	return Data.getId();

}

void kNode::addProperty(char *prop){

	Data.addProperty(prop);

}

void kNode::addOperator(char *op){

	Data.addOperator(op);

}


void kNode::setId(char *id){

	Data.setId(id);

}

bool kNode::propertyExist(char *prop){

	return Data.propertyExist(prop);

}
#endif


Error 1 error C2143: syntax error : missing ';' before '*' c:\documents and settings\brett\my documents\visual studio 2008\projects\jarvis stage1\jarvis stage1\klist.h 22
Error 2 error C4430: missing type specifier - int assumed. Note: C++ does not support default-int c:\documents and settings\brett\my documents\visual studio 2008\projects\jarvis stage1\jarvis stage1\klist.h 22
Error 3 error C4430: missing type specifier - int assumed. Note: C++ does not support default-int c:\documents and settings\brett\my documents\visual studio 2008\projects\jarvis stage1\jarvis stage1\klist.h 22
Error 4 error C2143: syntax error : missing ';' before '*' c:\documents and settings\brett\my documents\visual studio 2008\projects\jarvis stage1\jarvis stage1\klist.h 23
Error 5 error C4430: missing type specifier - int assumed. Note: C++ does not support default-int c:\documents and settings\brett\my documents\visual studio 2008\projects\jarvis stage1\jarvis stage1\klist.h 23
Error 6 error C4430: missing type specifier - int assumed. Note: C++ does not support default-int c:\documents and settings\brett\my documents\visual studio 2008\projects\jarvis stage1\jarvis stage1\klist.h 23
Error 7 error C2143: syntax error : missing ';' before '*' c:\documents and settings\brett\my documents\visual studio 2008\projects\jarvis stage1\jarvis stage1\klist.h 24
Error 8 error C4430: missing type specifier - int assumed. Note: C++ does not support default-int c:\documents and settings\brett\my documents\visual studio 2008\projects\jarvis stage1\jarvis stage1\klist.h 24
Error 9 error C4430: missing type specifier - int assumed. Note: C++ does not support default-int c:\documents and settings\brett\my documents\visual studio 2008\projects\jarvis stage1\jarvis stage1\klist.h 24
Error 11 error C2614: 'kList' : illegal member initialization: 'lastNode' is not a base or member c:\documents and settings\brett\my documents\visual studio 2008\projects\jarvis stage1\jarvis stage1\klist.h 29
Error 12 error C2614: 'kList' : illegal member initialization: 'firstNode' is not a base or member c:\documents and settings\brett\my documents\visual studio 2008\projects\jarvis stage1\jarvis stage1\klist.h 29
Error 13 error C2065: 'kNode' : undeclared identifier c:\documents and settings\brett\my documents\visual studio 2008\projects\jarvis stage1\jarvis stage1\klist.h 39
Error 14 error C2065: 'currentNode' : undeclared identifier c:\documents and settings\brett\my documents\visual studio 2008\projects\jarvis stage1\jarvis stage1\klist.h 39
Error 15 error C2065: 'firstNode' : undeclared identifier c:\documents and settings\brett\my documents\visual studio 2008\projects\jarvis stage1\jarvis stage1\klist.h 39
Error 16 error C2065: 'kNode' : undeclared identifier c:\documents and settings\brett\my documents\visual studio 2008\projects\jarvis stage1\jarvis stage1\klist.h 40
Error 17 error C2065: 'tempNode' : undeclared identifier c:\documents and settings\brett\my documents\visual studio 2008\projects\jarvis stage1\jarvis stage1\klist.h 40
Error 18 error C2065: 'currentNode' : undeclared identifier c:\documents and settings\brett\my documents\visual studio 2008\projects\jarvis stage1\jarvis stage1\klist.h 42
Error 19 error C1903: unable to recover from previous error(s); stopping compilation c:\documents and settings\brett\my documents\visual studio 2008\projects\jarvis stage1\jarvis stage1\klist.h 42

all errors occur in kList.h
Last edited on
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