hi.. I want ask if I want but in the header of linked list acounter to count the nods for exampel or any thing .. I just want know how can I add the value in teh header the code of linked list is: HTML: // Node Declaration template <class TYPE> struct NODE { TYPE data; NODE *link; }; // End of Node Declaration // List Class Declaration template <class TYPE, class KTYPE> class List { private: NODE<TYPE> *head; NODE<TYPE> *pos; NODE<TYPE> *rear; int count; // Function Declarations bool _insert (NODE<TYPE> *pPre, TYPE dataIn); void _delete (NODE<TYPE> *pPre, NODE<TYPE> *pLoc, TYPE *dataOutPtr); bool _search (NODE<TYPE> **pPre, NODE<TYPE> **pLoc, int key); public: NODE<TYPE> *arry;//????? List (void); ~List (void); int addNode (int dataIn); bool removeNode (KTYPE key, TYPE *dataOutPtr); bool retrieveNode (KTYPE Argu, TYPE& dataOut); bool getNext (int fromWhere, TYPE& dataOut); int listCount (void); bool emptyList (void); bool fullList (void); }; // class List // End of List Class Declaration /* =============== List Constructor ============== Initialize the list. Pre Class is being instantiated Post Class instantiated and initialized */ template <class TYPE, class KTYPE> List<TYPE, KTYPE> :: List (void) { // Statements head = NULL; pos = NULL; rear = NULL; count = 0; } // List Constructor /* ==================== addNode =================== Inserts data into linked list. Pre dataIn contains data to be inserted Post Data inserted or error Return -1 if overflow, 0 if successful, 1 if duplicate key */ template <class TYPE, class KTYPE> int List<TYPE, KTYPE> :: addNode (int dataIn) { // Local Definitions bool found; bool success; NODE<TYPE> *pPre; NODE<TYPE> *pLoc; // Statements found = _search (&pPre, &pLoc, dataIn); if (found) // Duplicate keys not allowed return (+1); success = _insert (pPre, dataIn); if (!success) // Overflow return (-1); return (0); } // addNode /* ===================== _insert ==================== Inserts data into a new node in the linked list. Pre Insertion location identified by pPre dataIn contains data to be inserted Post data inserted in linked list or overflow Return true if successful, false if overflow */ template <class TYPE, class KTYPE> bool List<TYPE, KTYPE> :: _insert (NODE<TYPE> *pPre, TYPE dataIn) { // Local Definitions NODE <TYPE> *pNew; // Statements if (! (pNew = new NODE<TYPE>)) return false; pNew->data = dataIn; pNew->link = NULL; if (pPre == NULL) { // Adding before first node or to empty list. pNew->link = head; head = pNew; } // if pPre else { // Adding in middle or at end pNew->link = pPre->link; pPre->link = pNew; } // if else // Now check for add at end of list if (pNew->link == NULL) // Adding to empty list. Set rear rear = pNew; count++; return true; } // _insert /* ================== removeNode ================== Removes data from linked list. Pre dltkey is identifier of node to be deleted pDataOut is pointer to data variable to receive a copy of the deleted data Post data copied to output variable and node deleted or not found Return false if not found true if deleted */ template <class TYPE, class KTYPE> bool List<TYPE, KTYPE> :: removeNode (KTYPE dltkey, TYPE *pDataOut) { // Local Definitions bool found; NODE<TYPE> *pPre; NODE<TYPE> *pLoc; // Statements found = _search (&pPre, &pLoc, dltkey); if (found) _delete (pPre, pLoc, pDataOut); return found; } // removeNode /* =================== _delete ================== Deletes data from a linked list and returns data to calling module. Pre pPre is a pointer to predecessor node pLoc is a pointer to target node pDataOut is pointer to output data area Post Data have been deleted and returned Data memory has been recycled */ template <class TYPE, class KTYPE> void List<TYPE, KTYPE> :: _delete (NODE<TYPE> *pPre, NODE<TYPE> *pLoc, TYPE *pDataOut) { // Statements *pDataOut = pLoc->data; if (pPre == NULL) // Deleting first node head = pLoc->link; else // Deleting any other node pPre->link = pLoc->link; // Test for deleting last node if (pLoc->link == NULL) rear = pPre; count--; delete pLoc; return; } // _delete /* =================== retrieveNode ================== Interface to search function. Pre key is the search argument dataOut is variable to receive data Post dataOut contains located data if found if not found, contents are unchanged Return true if successful, false if not found */ template <class TYPE, class KTYPE> bool List<TYPE, KTYPE> :: retrieveNode (KTYPE key, TYPE& dataOut) { // Local Definitions bool found; NODE <TYPE> *pPre; NODE <TYPE> *pLoc; // Statements found = _search (&pPre, &pLoc, key); if (found) dataOut = pLoc->data; return found; } // retrieveNode /* ==================== _search =================== Searches list and passes back address of node containing target and its logical predecessor. Pre pPre is pointer variable for predecessor pLoc is pointer variable for found node key is search argument Post pLoc points to first node equal/greater key -or- null if target > key of last node pPre points to largest node smaller than key -or- null if target < key of first node Return true if successful, false if not found */ template <class TYPE, class KTYPE> bool List<TYPE, KTYPE> :: _search (NODE<TYPE> **pPre, NODE<TYPE> **pLoc, int key) { // Statements *pPre = NULL; *pLoc = head; if (count == 0) return false; // Test for argument > last node in list if (key > rear->data) { *pPre = rear; *pLoc = NULL; return false; } // if while (key > (*pLoc)->data) { // Have not found search argument location *pPre = *pLoc; *pLoc = (*pLoc)->link; } // while if (key == (*pLoc)->data) // argument found--success return true; else return false; } // _search /* =============== emptyList ============== Returns Boolean indicating whether the list is empty. Pre Nothing Return true if empty, false if list has data */ template<class TYPE, class KTYPE> bool List<TYPE, KTYPE> :: emptyList (void) { // Statements return (count == 0); } // emptyList /* =================== fullList ================== Returns Boolean indicating whether the list is full or has room for more data. Pre Nothing Return true if full, false if room for another node */ template <class TYPE, class KTYPE> bool List<TYPE, KTYPE> :: fullList (void) { // Local Definitions NODE<TYPE> *temp; // Statements if (temp = new NODE<TYPE>) { delete temp; return false; } // if // Dynamic memory full return true; } // fullList /* ==================== listCount ==================== Returns integer representing number of nodes in list. Pre Nothing Return count for number of nodes in list */ template <class TYPE, class KTYPE> int List<TYPE, KTYPE> :: listCount(void) { // Statements return count; } // listCount /* ====================== getNext ===================== getNext traverses a linked list. Each call either starts at the beginning of the list or returns the location of the element in the list that was last returned. Pre fromWhere is 0 to start at the first element dataOut is reference to data variable Post if another element, address placed in output area Return true if another element located, false if end of list */ template <class TYPE, class KTYPE> bool List<TYPE, KTYPE> :: getNext (int fromWhere, TYPE& dataOut) { // Local Definitions bool success; // Statements if (fromWhere == 0) { // Start from first node if (count == 0) success = false; else { pos = head; dataOut = pos->data; success = true; } // if else } // if fromwhere is zero else { // Continue from current position if (pos->link == NULL) success = false; else { pos = pos->link; dataOut = pos->data; success = true; } // if else } // if fromWhere else return success; } // getNext /* =============== Destructor ============== Deletes all data in list and recycles memory Pre List is being deleted Post Data and class structure have been deleted */ template<class TYPE, class KTYPE> List<TYPE, KTYPE > :: ~List (void) { // Local Definitions NODE<TYPE> *deletePtr; // Statements if (head) { while (count > 0) { deletePtr = head; head = head->link; count--; delete deletePtr; } // while } // if } // Destructor and thanks :shy:
my secund qustion : if I want choos arandom node from the list how can I do it ?? I bild a pointer then I saide : TYPE data; NODE<TYPE> *seek; data.key=abs(rand() % ??); seek->data.key; I gut loste !! becuse how can I know if the pointer dident go out of the rang?
Storing the size of a linked list is not a good idea as it is extra data that must be kept up to date with the list. Normally to determine the length of the list you would walk it from start to finish just counting each step. But there's nothing to stop you doing that if you want; just make sure that every function that adds or removes one or more nodes modifies the counter accordingly. If you know the size of the list then picking a random entry is easy. rand() % size will pick a random number in range, then you walk that many steps down the list. Lists are not arrays and do not use array semantics, so there is no "quick" way to the data. You can check if the pointer doesn't go out of range by checking for the NULL terminator. At the end of the list, link should be NULL, so if you're still walking when you encounter it you know your size variable has become out of step with the array (i.e. it doesn't represent the true length).
ammmm... I use the function listcount like this: HTML: data.key=abs(rand()% A.listCount() ); can I use function retrieveNode to do the jub to Ensures the existence within the list?? EX: HTML: while(!A.retrieveNode (data.key, dataOut))
I don't know. Does it work if you try it? (Why do you need to ask me this? It's your code; you know how it works.)
