LinkedList* listPtr = new LinkedList;
listPtr->addNode(3);
listPtr->addNode(4);
listPtr->addNode(6);
listPtr->print(std::cout);
delete listPtr;
listPtr->addNode(5);
listPtr->print(std::cout);
When I run the program it outputs
{ 3, 4, 6 }
{ 5 }
Why does the LinkedList object that listPtr is pointing to not get destroyed??
If i have a pointer array of classes, e.g. MyClass *foo; and if i try to delete this pointer delete [] foo; does it call a destructor of a class, or wahat happens? this is because i have another pointers in that class which are cleared in destructor.
View 1 Replies View RelatedBasically, I have a LIST that is saved in a CSV file, and I need to remove a particular record after using the search feature (which populates the fields from the CSV file... i.e. ID, Name, etc...).
I am able to get the details that are in the text fields by using a search feature. This is then put in:
logic.remove(tempIndividual)
In class myLogic.cs, then I have this method:
this.individual.Remove(tempIndividual)
Upon debugging, I can see that tempIndividual is populated with the correct data. However, I need to remove this data from the CSV file. Am I on the right track, or totally off? Maybe it is not complete, cause I can't get to the part where it actually removes the data from the CSV, or at least I'm not sure if .Remove is able to do it on its own.
I am writing a program to list the 8 planets, then you select which planet you want. it gives you the mass of the planet, the radius, then you use the mass and radius of the planet to find the surface area (sphere formula) and the density of the planet. Along with those options, you have to add and delete a planet from the list and then sort them alphabetically. All i am having trouble with is the adding and deleting part. The code the adding and deleting from the list would go in cases 9 and 10.
heres my code as of this point.
#include <iostream>
#include <cmath>
#include <vector>
#include <algorithm>
#include <set>
using namespace std;
void print(const std::string& item) {
[Code] ....
I'M TRYING TO DELETE FROM THE END OF A LINKLIST...Actually I delete the last node but the problem is that I lost the end of the list, in other words my list leaved of pointing to NULL.I really don't know how to fixed, (it was more easy to delete from head)
Code :
void linkedstack::pop() {
if(head==NULL){
cout<<"The linklist is empty"<<endl;
return;}
else {
node *current=head;
[code]....
If I have a linked list, how can I delete it at the end of my program to free the memory taken up. I know I have to use delete but not sure how to use it in this case.
Here is the code that I have:
#include <iostream>
#include <cstdlib>
using namespace std;
struct Numlist {
int num; //Number
Numlist * next; //Pointer to the next node
[code]....
i am writing a program to list the 8 planets, then you select which planet you want. it gives you the mass of the planet, the radius, then you use the mass and radius of the planet to find the surface area(sphere formula) and the density of the planet. along with those options, you have to add and delete a planet from the list and then sort them alphabetically. All i am having trouble with is the adding and deleting part. the code the adding and deleting from the list would go in cases 9 and 10.
heres my code as of this point.
#include <iostream>
#include <cmath>
#include <vector>
#include <algorithm>
#include <set>
using namespace std;
void print(const std::string& item) {
[Code] ....
I have a struct with some select student information. My wish is to be able to have the user type in a surname from the list, and for that entry to be deleted. However I am slipping up for some reason.
Here is the start of my program showing my struct:
Code:
#include <stdio.h>
#include <string.h>
#define NAME_LEN 30
#define LINE_LEN 80
struct record {
[Code] ....
I get the following errors in my while loop as well as the if statement below that loop:
-invalid operands to binary !=
-invalid type of argument '->'
If p is a pointer pointing a node to be deleted, then what's wrong in the following code:
cout << "Do you want to delete this record? (y/n) ";
if (getch() == 'y' || getch() == 'Y'){// Delete record.
if (p == *ph){//If first node is to be deleted.
*ph = (*ph)->next;
delete p;
[Code] .....
I need to delete the Nth node from a doubly linked list. I know I just cant delete it out right. I have all the goodies including a templetized node class. This is the code we're given:
template <typename T>
void doublyLinkedList<T>::deleteKthElement(const int item) {
}
It accepts an int, and should go to the Nth node and delete it.
I am trying to delete a node from the end of a Linked List but I have some problems. Every node has it's unique code. Here is what I do:
1. Ask the user for the unique code of the node.
2. Ask him if he wants to change the data in it or delete the whole node.
3. If he chooses to delete it, I do this:
//let's say that temp1 points to the node
List *temp2 = temp1;
temp1 = temp1->next;
delete temp2;
And it's just not deleting the node.
I would like my function to return the data that was deleted. I have this code at the moment, where value_type is just an alias for int at the moment:
node::value_type linkedlist::removeFromHead(){
node* temp_head;
node::value_type data;
data = head_ptr->getData();
[Code] .....
When I try to use this function though, I get a segfault.
I am creating a Linear linked list in c++. I've written all the functions for it, but now I want to try and do them using recursion.
I managed to make functions for adding and displaying nodes on the list, but I am stuck on the function for removing nodes. First I want to try and write a function the removes the last item on the list. But for some reason my code isn't working properly.
Here is the code :
void removeLastItem(node * &head) {
if(!head) {
delete head;
head = NULL;
[Code] ....
NODE - My structure name
NEXT - The pointer to next element.
HEAD - The first (head) pointer.
The couts in the if statements are just for testing. In fact after I Run my program it does as it is supposed - enters the second if /b]case as many times as there are elements and then executes the first [b]if statement. But for some reason it does not delete the actual node.
I was having problems changing the value of my head node I passed it as an argument as head which would be the address. The parameter was defined as struct node *head. like this
bool deleteNode(struct node *head, struct node *delptr)
I tried manipultaing pointer values to change head node value but it did not work. I saw some code online which used pointer to pointers(in code below) to change head node value it worked I dont fully understand why. Would like better understanding of why.
Would also like to know why the argument call needed &head instead of just head.
remove = deleteNode(&head,found); opposed to remove = deleteNode(head,found);
#include "stdafx.h"
#include<iostream>
struct node{
[Code].....
In this book, item 3 is about never treat arrays polymorphically. In the latter part of this item, the author talks about the result of deleting an array of derived class objects through a base class pointer is undefined. What does it mean? I have an example here,
Code:
class B
{
public:
B():_y(1){}
virtual ~B() {
cout<<"~B()"<<endl;
[Code] ....
This sample code does exactly what I want. So does the author mean the way I did is undefined?
i am having trouble figuring out inorder traversal in this assignment. I was given this function definition in the homework i have to declare it. The problem i am having is how to use pointer to function to traverse the list.
void CBSTree<NodeType>::InOrderTraversal(void (*fPtr)(const NodeType&)) const;
void CBSTree<NodeType>::InOrder(const CTreeNode<NodeType> *const nodePtr
,void (*fPtr)(const NodeType&)) const;
//nodePtr is a pointer to a NodeType object (this is a recursive function, initially this points to the root).
//fPtr is a pointer to a non-member function that takes a const reference to a NodeType object as input, and
//returns nothing
I know without the pointer to function parameter it will be like this.
void InOrder(CTreeNode *nodePtr)
{
if(nodePtr != NULL)
{
InOrder(nodePtr->left);
cout<<nodePtr->value;
InOrder(nodePtr->right);
}
[Code]...
I just don't know how to traverse inorder with the function definition i am given.
I've been playing around with making a linked list in C and am having trouble adding to the beginning of the list. For the add_beg() function: the statement "head = newNode" only works locally. This leads me to believe this is a pointer problem. However, the add_end() function works correctly. Ideally, I would like to print "0 1 2 3 4" after using the add_end(root, 0). Currently, print only gives me "1 2 3 4".
#include <stdio.h>
#include <stdlib.h>
//Create a node struct
typedef struct node {
//data
int val;
[Code] .....
I have a the following in a header file.
Code:
struct SortedList{
void * data;
struct SortedList * next;
struct SortedList * previous;
int (*compareFunc)(void *, void *);
void (*destructor)(void *);
[Code] ....
In a .c file, I implemented the SLCreate function.
Code:
SortedListPtr SLCreate(CompareFuncT cf, DestructFuncT df){
struct SortedList item;
item.data = NULL;
item.next = (struct SortedList *) malloc(sizeof(struct SortedList));
[Code] ....
In main.c, I try to do the following:
Code:
SortedListPtr list = SLCreate(&compareInts, &destroy);
A bunch other code that does not alter list or it's contents at all.
struct SortedList item = (*list);
void * data = item.data;
if (data != NULL) {
printf(Why did data become not null???
"); }
How come my variable data became not null anymore when I haven't altered it at all....
Why is it sufficient to only have a pointer to the last node of a doubly linked list?
View 1 Replies View RelatedWhy is it sufficient to only have a pointer to the last node of the list?
View 3 Replies View RelatedI'm having a bit of an issue here. I have a linked list where each node contains a pointer to a string (which has been malloc'd when the node was created and inserted) and a pointer to the next node in the linked list.
I'm creating a function which will free the node (or effectively delete it). However, I'm receiving a free(): invalid pointer error.
My function:
void removeNode(node *(*nodeToRemove))
{
free((*nodeToRemove)->data);
(*nodeToRemove)->next = NULL;
free(*nodeToRemove);
}
Is this how I should go about freeing this node?
This code works:
//void Fighter::LoadAnimation(...){
std::list<SCML_SFML::Entity*> entities;
for(std::map<int, SCML::Data::Entity*>::iterator e = data.entities.begin(); e != data.entities.end(); e++) {
SCML_SFML::Entity* entity = new SCML_SFML::Entity(&data, e->first);
entity->setFileSystem(&fs);
entity->setScreen(&window);
entities.push_back(entity);//problem line
}
}
But if i change entities to a member variable, std::list<SCML_SFML::Entity*> Fighter::m_entities, it does not. Instead i get a write access violation when i try to push_back(entity). i need it to be a member variable because i need to use it in other member functions.
I am having trouble modifying a linked list. I am writing a function to delete the last node from the linked list, but it gave me incompatible types error.Here is my struct:
Code:
typedef struct PCB{
int id;
struct PCB *next;
struct PCB *prev;
}PCB_rec, *PCB_p;
Here is my function to delete the last node (given the pointer is pointing at the last node of the list):
Code:
void del_last_node(PCB_p *process_list){
PCB_p temp = process_list;
if (temp->prev != NULL){
temp = temp->prev;
[Code] ....
And here is how I called the function:
Code: del_last_node(&process_list);
It gives me the following errors:
initialization from incompatible pointer type at line:
PCB_p temp = process_list
assignment from incompatible pointer type at line:
process_list = temp
I am getting and infinite loop for loop pointer variable current which points to head and is incremented by current->next in while loop. I use the pointer variable the same way in my display routine and it works. Here is listing of code.
#include "stdafx.h"
#include<iostream>
struct node{
int data;
node *next;
[Code] .....
Why would it be cumbersome to maintain an additional pointer to the first node in a doubly linked list?
View 1 Replies View RelatedI'm trying to write a function called 'set' that sets the value of the i'th cell to val on my linkedList, and then returns the previous contents. I am stuck on it due to compiling errors:
This is my Node struct:
#ifndef NODE_H
#define NODE_H
#include <iostream>
template <typename T>
struct Node {
friend std::ostream &operator <<(std::ostream &os, const Node<T> &node) {
[Code] ....
The following is my set function:
template <typename T>
T set(Node<T> *head, int i, const T &val) {
for(int n = 0; n < i; n++)
if(head == val) {
val = i;
} return val;
} #endif
When I try to call it in the main() I get these errors:
node_utils.h: In function ‘T set(Node<T>*, int, const T&) [with T = int]’:
node_demo.cpp:26:38: instantiated from here
node_utils.h:161:2: error: ISO C++ forbids comparison between pointer and integer [-fpermissive]
node_utils.h:162:3: error: assignment of read-only reference ‘val’
So, I understand that I can't compare head & val on my if-statement -- But what do I do?
