Object slicing

I have a program as bellow:

#include<iostream.h>
#include<conio.h>
class A
{
    public:
    int x;
    A()
    {
        x=10;
    }
};

class B:public A
{
     protected:
     int y;
     public:
     B()
     {
        y=30;
     }
};

void main()
{
    A obj1;
    B obj2;
    obj1=obj2;
    cout<<obj1.x;
    cout<<obj1.y;
    getch();
}

The error message is "y is not member of A"

Can any one solve this problem?

View Answers

August 23, 2012 at 3:55 PM

There is nothing to solve here. The error message displays correct that "y is not member of A".

When you assign a derived class's instance into the base class only that part, which are present in the base class are copied, rest are not copied. this is called Object Sliced. because here obj2 get sliced and stored in obj1.

The main reson for this is, it is not possible (or meaningful) in any statically typed language for a superclass instance to contain subclass member variables.

Ads

Advertisements

object of object class
object of object class what do u mean by "object of object class

object creation
object creation when will java object is created? is it at runtime or compiletime

Object Oriented
Object Oriented C++ is Purely object oriented or not .Then why java called purely object oriented

Object reference not set to an instance of an object
Object reference not set to an instance of an object Object reference not set to an instance of an object

Object
Object An object...). In an object, variables store values for later use and methods are the unit... are the basic units of the object-oriented programming. Objects are the part of our day

Session Object
Session Object Why do we require Session Object? Hello.... The session object is used by the developers to store and retrieve user's related data such as login details. The javax.servlet.http.HttpSession object

ArrayList object
ArrayList object i have am ArrayList object it containg data base records in it, now i want to display this ArrayList object data in my jsp programe, plz help me

object as argument
object as argument what happens when we pass a object into a method???if java is pass by value how does this makes a difference.....pllzzz give me more clarification on why we pass objects in a margument

Java object
Java object Which class should you use to obtain design information about an object

Object Creations
Object Creations String a[][]=new String[10][20]; The above line how many objects are created

Java object
Java object What is mutable object and immutable object? An Immutable object is a kind of object whose state cannot be modified after it is created. This is as opposed to a mutable object, which can be modified

Session Object
Session Object What is the Max amount of information that can be saved in a Session Object ? There is no such limit on the amount of information that can be saved in a Session Object. The only limit is the Session

object array
object array Hi i have array that is object[] obj= { new string("hi"), new vector().add(10), new hashmap().setkey()} display(obj); display(object{[] obj) {} Now my question is what is the string length and how to retrieve

Vector object[]
Vector object[] I want to create payslip in java public Vector...(); Object[] value = new Object[] {"Employee Name",f.ename.getSelectedItem()}; rec.add(value); value = new Object[] {"Mary-Kate Olsen", "Ashley

class and Object
class and Object how many classes,References and objects in this following statement.... A a=new B(); Hi, In the statement: A a=new B(); There are 2 classes, Class A and Class B. References : 1 (Object of B

implect object
implect object how i implment implect object Hi Friend, Please visit the following links: http://www.roseindia.net/help/java/o/jsp-implicit-objects.shtml http://www.roseindia.net/jsp/jspfundamentals.shtml Thanks

constructor or object
constructor or object object or construct which create first? A constructor is always created first. Here is an example: class Example { Example(String st){ System.out.println(st); } public

object and method
object and method a college would like to automate managing courses offered to students. initially only three courses are involved. each courses has... and an application that creates the necessary object

Class and object
the object of subclass Thanks

Java Object
Java Object Object is the basic entity of object oriented programming language. Object... properties of the class or its group. Java object is an instance of the class. It takes

What is an object's lock and which object's have locks?
What is an object's lock and which object's have locks? Hi, What is an object's lock and which object's have locks? Thanks

View object in JSF
View object in JSF What is view object

Java object clone
Java object clone What is criteria for a object to get cloned

How to disable an HTML object?
How to disable an HTML object? How to disable an HTML object

assign object properties
assign object properties How do you assign object properties

Date object using JavaScript
Date object using JavaScript What's the Date object using JavaScript

Potential leak of an object XCode
Potential leak of an object XCode What is potential leak of an object XCode

implementation object in C
implementation object in C how to create and implement an object in C

use of object tag
use of object tag how to use object tag in html

Ads