Monday, February 20, 2012

What is Object Slicing in C++ ?

Object slicing: when a derived class object is assigned to a base class object. only base class data will be copied from derived class and derived data will be sliced or ignored. This will occur in C++ , if you try to use call by value. see the sample code in c++.

Object slice prevention:
  • Object slicing can be prevented by making the base class pure virtual, so that base instance will not be allowed.
  • object slicing can't be occurred, if pointers or reference to the objects used, as both pointers of the same size

class base{

int a;
a = 10;
class derive: public base
int b;

int main()
base b;
derive d;
cout< < "size of base class is "< < sizeof(b)< < endl;
cout< < "size of derive class is  "< < sizeof(d)< < endl;
cout< < "size of b class is "< < sizeof(b)< < endl;

size of base class is 4
size of derive class is 8
size of b class is 4

From the above sample code, contents of the base class are one int data type and where as for derived class are two int data types. so size of the derived class is more than the base class. and in the example, derived instance is assigned to base instance, so base instance only takes the base contents and it will slice or ignore the extra int data type in derived class.
From the output, the size of the base object is four and size of the derived object is eight. we can observe that even after assigning the derived object to the base object, the size of the base object is four only. it sliced the extra four bytes from the derived object.


Anonymous said...

Output is not changed when i assigned the derived class object to base class object....

Anonymous said...

hey u can easily see that the size of base class is not changed after the assignment although derived class object is assigned to it... that means only the base class part is copied to base class object and derived class object is ignored.

Goverment of india Parliamentry OR Presidential said...

Where is display()

Chanduthedev p said...

display() function not required, for testing I added in my local system, just copy paste error ;-)

Anonymous said...

Find similar answers here:

Slicing means that the data added by a subclass are discarded when an object of the subclass is passed or returned by value or from a function expecting a base class object.

Explanation: Consider the following class declaration:

class baseclass
baseclass & operator =(const baseclass&);
baseclass(const baseclass&);
void function( )
baseclass obj1=m;
As baseclass copy functions don't know anything about the derived only the base part of the derived is copied. This is commonly referred to as slicing.

Santhi P said...

Object slicing has been explain well here. Thanks for the information! You can find more on object slicing with examples here below.

Object slicing in Cpp with examples

subha said...

keep up the good work. this is an Assam post. this to helpful, i have reading here all post. i am impressed. thank you. this is our digital marketing training center. This is an online certificate course keep it up
Ai & Artificial Intelligence Course in Chennai
PHP Training in Chennai
Ethical Hacking Course in Chennai Blue Prism Training in Chennai
UiPath Training in Chennai

divya said...

Well! If you’re not in a position to customize employee payroll in QuickBooks Payroll Tech Support Number which makes the list optimally, in QB and QB desktop, then read the description ahead. Here, you will get the determination of numerous type of information that which you’ve close at hand for assisting the setup process with comfort. keep it up guys.
Ai & Artificial Intelligence Course in Chennai
PHP Training in Chennai
Ethical Hacking Course in Chennai Blue Prism Training in Chennai
UiPath Training in Chennai

Keerthi SK said...

I was following your blog regularly and this one is very interesting and knowledge attaining. Great effort ahead. you can also reach us for
web design company in chennai
web development company in chennai
website designers in chennai
website designing company in chennai
web design in chennai
website development company in chennai

Vidhyamenon said...

Useful blog, keep sharing with us.

Why You Should Choose Appium Server
Why do we need Appium

Offshore software development company said...

Good Job !!! thanks for sharing.

Popular Posts