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?
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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?
I am trying to use web api in order to return custom json response keys. For this i have return a custom class to return json response
Custom Class:
using System;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
[Code].....
I'm currently creating a text-based RPG, to get myself back into learning C++ again. The problem seems to be with the if-else ladder of statements, the user selects which race they wish to play as, which as a result creates the appropriate object for that race.
This is the character selection option code:
std::cout << "Please select a race: Human [1], Elf [2], Dwarf [3] or Orc [4]
";
std::cout << "Race selection: ";
std::cin >> race_selection;
std::cin.ignore();
switch (race_selection) {
[Code] .....
The problem here is, regardless of which race I use using the above switch statement, the Human object always seems to be created, instead of the object for the desired race.
make a class that you can make only one Object of it.
For example if you have Class A.
Let's say you create one object A* a=new A();
Now the next time you, try to create another object. For example:
A* b=new A(); What will happen is that b will get the same object (or reference) as a. In other words hey'll be pointing towards the same place. So basically you'll only have one object of it created. I tried doing it but I couldn't quite make it.
Here is what I tried: (but couldn't complete the exercise)
class God
{
public:
static int num;
static God* god;
[Code]....
I am to first increment data members of object that has not created dynamically (i have done with this part),now i have created object dynamically and how to increment its data which i have passed as argument as:
obj3 = new manage(35 , 36)
Code:
m_vRenderObjects.push_back(new Objects(mOperatorMesh));
/// this is never called
~Objects(void) {
OutputDebugStringA("Cleanup Objects
");
if (StateMachine != NULL)
[Code] ....
This leads to ugly memory leaks.
public class Customer
{
public int Id { get; set; }
public string Name { get; set; }
public List<Order> Orders { get; set; }
public Customer() {
Orders = new List<Order>();
}
}
This object is called as
var cust = new Customer
{
Id = 1, Name = "Khatana", [b]Orders.Add(new Order())[/b]
}
I want to ask, Orders.Add(new Order()) is a wrong way, but why..!!... as List<Order> already has been initialized in Customer constructor, then why it is again required to be initialized in object initialization.
Is this a correct way
List<Order> orders = new List<Order> {aaa.....bb....cc};
var cust = new Customer
{
id = 1, Name = "Khatana", Orders = new List<Order> { orders }
}
Why we need to initialize a list in an object initialization, where as the list has been already initialized in object constructor.
is it possible to get object name in the constructor? I would like to initialize an object of circle class without any arguments and put some pretty lines in constructor to get and save as table of chars the name of creating object. Is it possible? I work with MSVS2012.
View 4 Replies View RelatedHere is my issue: I am making a simple audioplayer in Xamarin.android but i want every time i change the track to make a crossfade effect. So im using 2 mediaplayers at the same time for the fade. The problem is that im defining one time the players and i pass the player as a parameter like this:
public MediaPlayer player = null;
public MediaPlayer player2 = null;
....
If i have to fadeout the player and start the next one im doing it like this:
if (player != null){
if (player.IsPlaying) {
cts = new CancellationTokenSource();
token = cts.Token;
FadeOut (player, 2000 ,token);
[Code] .....
So my problmem is that player and player2 remain always null. Why? i guess c# creates a copy of player and player2 and use this one. How i can pass a mediaplayer as parameter and always use only player and player2?
sth is in my mind.
fast way of initializing an object through constructor is
Fred::Fred() : x_(whatever) { }
slow way
Fred::Fred() { x_ = whatever; }
ok. i accept it is faster but why?? what is the difference compiler does.
Is there a way to copy a derived class object thru a pointer to base?
For example:
class Base { public: Base( int x ) : x( x ) {}
private: int x; };
class Derived1 : public Base { public: Derived( int z, float f ) : Base( z ), f( f ) {}
private: float f;};
class Derived2 : public Base { public: Derived( int z, string f ) : Base( z ), f( f ) {}
[Code] ....
The question is whether *B[0] would be a Derived1 object and *B[1] a Derived2 object?If not, how could I copy a derived class thru a pointer to the base class?
I have a question about the default constructor.
To my best understanding, the compiler will provide me with a deafult constructor only if there are no any user defined constructors, at all. Now consider the following code:
Code: class MyClass
{
private:
int m_data;
public:
MyClass(int init):m_data(init){cout<<"Ctr called"<<endl;}
[Code] ....
How is it that suddenly, there is a default constructor?
I am trying to pass an object to an inherited clas by a constructor. I am having Cboard my board and i need to pass it to the object Cpawn.
Here under is my code:
main
Code:
#include<iostream>#include "Cboard.h"
#include "Cpawn.h"
#include "Cpiece.h"
void main(){
char location[50];
[Code] ....
I have a program that has a base class 'control' and there are 2 dervied classes 'button' and 'textbox'. How do i make a constructor in the 'button' or 'textbox' that initializes a pointer of the data type 'control' to point to the object that invokes the constructor. the code should look like this
class control {
//data
} class button:public control {
buton() {
//code for the constructor
}
}
actually i have an array of pointers of the type 'control' and as soon as any instance of a control like button or textbox is created the constructor should make an element of the array to point to the instance
I am creating a Matrix class, and one of the constructors parses a string into a matrix. However, printing the result of the constructor (this->Print()) prints what I expect, and an <object_just_created>.Print() call returns bogus data. How is this even possible?
Snippets below:
Matrix::Matrix(const string &str) {
// Parse a new matrix from the given string
Matrix r = Matrix::Parse(str);
nRows= r.nRows;
nCols= r.nCols;
[Code] ....
in the driver program, here are the two successive calls
Matrix mm6("[1 2 3.8 4 5; 6 7 8 9 10; 20.4 68.2 1341.2 -15135 -80.9999]");
mm6.Print();
// mm6.Print() calls bogus data, -2.65698e+303 at each location. The matrix's
// underlying array is valid, because printing the addresses yields a block
// of memory 8 bits apart for each location
This keeps giving me the error
ecg.h:18:11: error: field "next" has incomplete type
How do I do what I need? It does the same thing whether I use a class or a struct. This is C++ code
struct ECG_node {
double voltage;
clock_t time;
ECG_node next;
[Code] .....
I'm trying to pass an reference of the object ifstream to my constructor as such:
// myClass.cpp
int main(){
ifstream file;
myClass classobj = myClass(file);}
I am defining the constructor as follows, in myClass.cpp:
myClass::myClass(ifstream &file){
// do stuff
}
I get the error of "No overloaded function of myClass::myClass matches the specified type."
Also, when I build the program, it tells me "syntax error: identifier 'ifstream'"
Also, I made sure I included this:
#include <iostream>
#include <fstream>
#include <sstream>
What am I doing wrong? How can I pass an ifstream reference to my constructor?
Write a constructor that initializes a new inventory object with the values passed as arguments, but which also includes a reasonable default value for each parameter.
#include "stdafx.h"
#include <iostream.h>
#include <stdio.h>
#include <string.h>
class inventory {
[Code] ....
I am not trying to get my homewotk done, just to understand my errors. It complies without problem. But doesn't run.
I have a method to take a Tile object and make an instances of it based on some data from the original object. Than it is suppose to manipulate the a specific instance and save the results. The first loop through it works but it changes all instance as well as the base.
public static int recurse(int count, Tile[,] b,Huristic h,int check) {
if (check==1) {
boardState.Add(B)/>;
return check;
} if (check == 0)
[Code] .....
#include "B.h"
class A {
public :
A()
{
s_b = new B();
b = new B();
[Code] ....
In my project i have seen static object as above . But not able to know what is the exact use of it and how they are different from general object .
a function returns a temporary object like
int myfun(){
int x = 0;
return x;
}
this function will return a temporary integer now void fun1(const int & num); this function can receive from myfun().BUT void fun2(int & num); this function cannot receive from myfun() Why is that, Moreover what is lifetime of a temporary object like one returned in myfun() ???
I have a combobox with Items 1024
2048
4096
8192
String cach = form.comboCache.SelectedItem.ToString();
I am using the above code to retrive an item selected by user,But this line is giving an exception "Null Reference Exception, Object reference not set to an instance of an object"
I am using session to pass object from controller to custom class in MVC Web API. here is my code, i am getting error at session.
public HttpResponseMessage Get()
{
var person = db.Persons.ToList();
[Code]....
In Visual Studio 2010 C++
I have a series of existing text objects
The text properties names are
item1_lbl,
item2_lbl,
item3_lbl,
….
Based on a selection I want to change an object. I generate the name of the object I want to change in a string so from this string is there a way to get a pointer to the correct text object that is same name?
Suppose I have two classes A and B so how to access object of class A in constructor of B's class as a parameter.
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