Classes

This is a discussion on Classes within the C++ Programming forums, part of the General Programming Boards category; if i have one class called Message.cpp and then another class called LinkedList.cpp and another class called Node.cpp and another ...

  1. #1
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    Classes

    if i have one class called Message.cpp
    and then another class called LinkedList.cpp
    and another class called Node.cpp
    and another class called FoundMessage.cpp
    How do i link these together to do the following..

    -> get messages from the Message.cpp class
    -> put the message's info into a Node
    -> The node is then inserted into the linkedlist
    -> in FoundMessage.cpp there is a function that finds a particular message in the linked list.

    assuming that i have all the code .. how would i go about this..
    im not sure how classes relate to each other and if there is any restrictions on calling another class's functions..

    any help?

  2. #2
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    so far im stuck with this happening
    i have a node.h and a node.cpp
    i also have linkedlist.cpp and linkedlist.h
    in linkedlist.cpp im calling a function that is in node.cpp..
    but i am getting this error
    Code:
    LinkedList.cpp:30: error: `makeNode' undeclared (first use this function)
    ??
    in linkedlist.cpp i also have #include "linkedlist.h" and #include "node.h"
    isnt this enough?
    thanks

  3. #3
    mustang benny bennyandthejets's Avatar
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    Post the code that gives the error.
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  4. #4
    VA National Guard The Brain's Avatar
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    just one quick note.. you might already know this.. but you might want to save your classes as .h header files... i.e. message.h

    just be sure to include
    Code:
    #include "message.h"
    along with your preprocessor directives (#include<whatever >) in your driver (.cpp) program.


    then.. compile your .cpp program.. and the header file will automatically be compiled along with your .cpp program.
    Last edited by The Brain; 08-01-2004 at 05:26 AM.
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  5. #5
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    im just reviewing my code now and it looks like one biggg mess....
    and im just falling into this huge pit of confusion..
    hopefully help is on the way

    ok heres my code

    Code:
    /*   NODE.H    */
    
    class Node {
     public:
            Node();
            ~Node();
            Node* makeNode(const char *s, int a, int b);
    
     private:
            string msg;
            int s;
            int t;
            Node* nextPtr;
    };
    Code:
    /*  NODE.CPP  */
    #include "node.h"
    
    Node * Node::makeNode(const char *s, int a, int b) {
    
            Node * newNodePtr = (Node *)malloc(sizeof(Node));
    
            if(newNodePtr == NULL) {
                    cerr << "Out of memory" << endl;
            }
            else {
                    newNodePtr->msg = s;
                    newNodePtr->t = a;
                    newNodePtr->s = b;
                    newNodePtr->nextPtr = NULL;
            }
            return newNodePtr;
    }
    Code:
    /*   LINKEDLIST.H   */
    
    #include "Node.h"
    
    class LinkedList {
     public:
            LinkedList(LinkedList* listPtr); // constructor
            void Insert(LinkedList* listPtr);
            void insertItem(LinkedList* listPtr, const char * s, int type, int status);
            int deleteNodes(LinkedList* listPtr);
    
     private:
            int count;
            Node* headPtr;
    };
    hopefully you can see from this, im TRYING to implement it so that i have a linked list of nodes.. not sure if that private member Node* headPtr should be LinkedList * headPtr or not...
    i want to be able to do things like..
    Code:
    Node * newNode;
    newNode->headPtr->msg = "hello";
    so im not sure if those declarations and the structure are correct..

    and finally the linkedlist.cpp where makeNode error (and many others) was occuring..

    Code:
    /*   LINKEDLIST.CPP    */ 
    
    #include "LinkedList.h"
    #include "Node.h"
    
    
    void LinkedList::insertItem(LinkedList* listPtr, const char * item, int type, int status) {
    
            Node* newNodePtr = makeNode(item, type, status);
            Node* prevPtr = NULL;
            if (position == 0)
            {
                    newNodePtr->nextPtr = listPtr->headPtr;
                    listPtr->headPtr = newNodePtr;
            }
            else
            {
                    prevPtr = setPosition(listPtr, position-1);
                    newNodePtr->nextPtr = prevPtr->nextPtr;
                    prevPtr->nextPtr = newNodePtr;
            }
            listPtr->count++;
    }

    i know thats heaps of code to take in.. hoep you can help

    THANKS

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