This is my class there is a problem with my copy constructor .. is that correct ??
struct Node {
Type info;
Node<Type> *next;
};
template <class Type>
class Queue
[Code] ....
class Base
{
char * ptr;
public:
Base(){}
Base(char * str)
[code].....
Obj1 is a derived class object where base class char pointer is initialized with "singh" and derived class char pointer is initilized with "sunil". I want to create Obj2 out of Obj1. Separate memory should be created for Obj2 char pointer (base part and derived part as well) and that should be initialized with the strings contained in Obj1.
Here the problem is: Derived class part can be initialized with copy constructor. How to initialize the base class char poniter of Obj2 with the base class part of Obj1. char pointers in
both the classes are private.
I tried using initializer list but could not succeed.
Is there some proper way to do this?
The following are the cases when copy constructor is called.
1)When instantiating one object and initializing it with values from another object.
2)When passing an object by value.
3)When an object is returned from a function by value.
I don't understand #2 How can and object be passed by value? when I think of passing object I think of passing by address or reference. explain
I don't understand #3 how can a function returned object by value I think of again passing by address or reference.
In the below program, how can copy the array n[] into Array[]. The below is not working..
#include <iostream>
using namespace std;
class arrayPlay {
[Code] .....
copy constructor. I'm not really understanding them. I have a base class called Vehicle and a derived class called Car.
class Vehicle
{
private:
int age;
[Code].....
I'm trying to test the new attributes and behavior of car but I think its not working because of the copy constructor. Its just not clicking. I also forgot that race car status is supposed to return yes or no, am I defining that right?
Class Car{
Private:
string* _ID;
bool _isFaulty;
int _location;
int _timer;
int _order;
vector<Road*> _roadPlan;
}
I want to implements Copy constructor (deep copy) and destructor, and I don't know how to treat the vector of pointers (Road is an object too)
Mor
Another thing, maybe I'll prefer using List instead of Vector, so i would like to see an implements of Copy constructor and destuctor with List too,
I want to copy over values from x to y, and its not possible as i cant use "y" as a index in my pointer array.
Code:
CellularPhoneStock::CellularPhoneStock(CellularPhoneStock &origObj){
this->phonez[nrOfPhones]->setColour = origObj.getColour();
/*this->model = origObj.model;
this->nrOfType = origObj.nrOfType;
this->price = origObj.price;*/
nrOfPhones++;
}
My questions is, how can I use origObj and phonez combined to use the function getColour() ?
Btw, phones = CellularPhone * phonez[30];
I was wondering that why in the below code, the copy constructor is called 2 times.
Code:
class A {
private:
static int count;
int age;
public:
A()
[code].....
I think that when f(a) is called, since I am passing this as value, no copy constructor should be called. The copy constructor should called when the return object "x" is assigned to:
A b = x;
why copy constructor called 2 times?
I can't find why it won't output the correct info for the array. I've looked until I am ready to throw the computer out the door. I'm at my wits end trying to get this to work right. I finally got it to quit killing the compiler, but it's doing this. The problem is in the insertBefore or insertAfter function calls and I don't think that my copy constructor is right.
#include <iostream>
#include <cstdlib>
#include <fstream>
#include <iomanip>
using namespace std;
typedef int eletype;
int const CAPACITY = 20;
[Code] ....
How do i write main test program to test the copy constructor and assignment operator in this program...how do i know if its working as its suppose to?i just want to know about copy and assignment operator..i have figured out the test program for other things..Here my program :
ListType.h
#ifndef LISTTYPE_H
#define LISTTYPE_H
#include<iostream>
class ListType{
public:
ListType(size_t=10);
ListType(const ListType&);
[Code] ......
I've been working on some project and I got to wondering when you know you need to use a copy constructor and an assignment operator. Is there a rule of thumb? I know there is the Rule of Three, but is there something that tells you when you need those three?
View 4 Replies View RelatedI have problems to put a list inside a linked list. I have the following conditions to fulfill:
- main.cpp can NOT be changed
- There must be an abstract base class 'shape'
- Methods such as area() and print() must be in code
- Constructors is as follow:
Point( double x, double y, double size)
Circle( double x, double y, double radie)
Rectangle( double x, double y, double width, double height)
Polygon( double x, double y, Vertex *varr, int num)
- There must exist a Linked list 'ShapeList':
ShapeList()
ShapeList( const ShapeList &shapes)
~ShapeList()
add( const Shape& s )
remove( const Vertex &v)
area()
print()
This is what I've created so far (Shape, ShapeList, Vertex):
main.cpp:
#include <iostream>
using namespace std;
#include "shapelist.h"
#include "vertex.h"
#include "shape.cpp"
[Code] ....
I'm trying to do deep copy for my constructor
List::List(const List& list)
{
if ( list.empty() )
[Code].....
I think I'm not really able to track the new node for this reason my app crashes.
ListNode* p = list._pFront ;
this is for the original node
p ->_data;
the data inside the original node. Each node has three pointers. One for the entire node which tracks whether the node in front or in the back. The other two for next and previous nodes.
I know everything works except my copy constructor! There are no errors. The program crashes when it goes to access the copy constructor. why the copy constructor isn't working?
#ifdef _MSC_VER
#define _CRT_SECURE_NO_WARNINGS
#endif
#include <cstring> // access to C str functions
#include "String.h" // access String class
using namespace std;
String::String( int size )// default constructor
[code].....
here is the list.h file
#include <iostream>
#include <iomanip>
#include <string>
using namespace std;
class Node {
[code]....
Ignore the optional part as i am not working with that at the moment. The problem is my program keeps crashing when deallocating. Not sure why.
I'm working on a project and I'm not quite sure how to implement the Copy constructor and Overloaded assignment operator.
This is what the instructions say if that matters at all: Since you have dynamic variables in your class, you should make sure that the big three are implements. You already have the destructor, but you will need to add a copy constructor and the overloaded assignment operator. This is simpler than it sounds, but it requires some thinking. You need to make sure that both the copy constructor and the assignment operator create new containers.
Here is my header file:
#ifndef CANDIDATELIST_H
#define CANDIDATELIST_H
#include "CandidateType.h"
#include <iostream>
[Code].....
I know I don't have much in these functions but I'm not sure how to apply them or if I'm even headed in the right direction.
Here is my code. It runs but after display result, it announce error
template <class T>
class LINKED_LIST {
private:
struct ListNode {
T data;
ListNode *next; // pointer to next node
[Code] ....
#include<iostream>
using namespace std;
class Cents {
public:
int m_nCents;
Cents(int nCents=0):m_nCents(nCents){
cout<<"Calling normal constructor with value:"; m_nCents = nCents;
cout<<m_nCents<<endl;
[code].....
Question is :Why is the overloaded copy constructor that I have written not getting called here?Internally default copy constructor is getting called.Thats why we get value of obj2.m_nCents as 37.
Code:
class Matrix4 {
Matrix4(float mat[4][4]) {
memcpy (m, mat, 16);
}
float m[4][4];
};
float m[4][4];
cam->getProj(m);
Matrix4 matProj(m);
The above snippet doesn't compile, correcting mistakes in syntax.
I have the following classes and 'dreaded diamond':
A
/
/
B C
/
/
D
|
|
E
Classes B & C both inherit from A using public virtual A.
E is the only concrete class. None of the classes are totally abstract.
Every class has a copy constructor.
All of the copy constructors are chained together through the initialization lists.
E correctly calls D's copy constructor.
D correctly calls B and C's copy constructors.
But neither B nor C call A's copy constructor, although A's default constructor is called. To reiterate B and C have a call to A's copy constructor in their initialization lists.
I guess A's default constructor is being called is because of virtual inheritence, but why isn't its copy constructor called (too)?
A's copy constructor includes some very important code and I could do with calling it. Should I call it from the concrete class' initialization list or is that considered bad form?
Go to this link : [URL] .....
Actually I am not getting one thing in this code that why they only provide the declaration of Copy constructor and Assignment operator...??
Is this example correct? This example from a book
Constructor of the Base Class
Person::Person(char* n="", char* nat="U.S.A", int s=1)
{
name = n;
nationality = nat;
sex = s;
}
Constructor of the Derived Class (inherited from the base class)
Student(char* n, int s=0, char* i=""):
Person(n, s)
Why the initialized list of the base class constructor doesn't match the initialized list of the derived class constructor? I know this book is a little bit old, I'm not sure if this wrong in VC++ 2010?
I was going through Singleton design pattern and get to know that objects can be created only by static function of that class and constructors are make private.
My question is, why assignment operators are not made private through which we can create a copy of already existing object.
I tried below code and assignment works, so I have new object sc3. I know that its referring to memory of sc1 but finally I was able to create object without using static function.
Also, why copy constructor not made as private.
Below is code:
#include <iostream>
using namespace std;
class Singleton {
private:
static bool instanceFlag;
[Code] .....
to initialize this object? Why C++ FAQ says no? Here is my code,
Code:
class A
{
public:
A(int x, char c);
A(int x);
[code] ....
I don't have any trouble to call the constructor A(int x, char c) from another constructor A(int x).
will copy constructor does object initialization using another already created object? I understand that it can be applied for object initialization and not for assignment.Is it correct?
View 10 Replies View RelatedLet's say I have a Car object , and it contains inner Engine object.
Code:
struct Car{
Engine mEngine;
};
In order to initialize the engine object NOT by the default constructor (if it has any) , we use initialization semantics:
Code:
Car::Car:
mEngin(arg1,arg2,...)
{
other stuff here
}
Now it gets tricky: Let's say a Car objects has 10 inner objects, each object has about 5 variables in it . Car is a base class for , e.g. , Toyota class. you don't want the Car class to have a constructor with 50 arguments. Can the inner objects of Car be initialized from the base class , e.g. Toyota?
Code:
class Toyota:
Car(...),
mEngine(...),
mGear(..)
{
...
};
The other options are:
1) like said , create a Car constructor which gets 50 arguments, then initialize Car as whole from Toyota - the code becomes less readable and less intuitive
2) Car constructor which get built-objects as arguments and initialize the inner objects with copy constructor . the code gets more readable but then you create many excess objects .