c++ get base class object from derived class pointer?

Question

Suppose I have Derived* derivedPtr;
I want Base baseObject from the derivedPtr;

Base baseObject = *derivedPtr; would create the baseObject with the appropriate Base class member variables?

Thank you

Community · Accepted Answer · 2017-05-23 12:19:53Z

3

Derived* obj = new Derived;
base objOne = (*obj) ;  // Object slicing. Coping only the  Base class sub-object
                        // that was constructed by eariler statement.

edited May 23, 2017 at 12:19

CommunityBot

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answered Mar 22, 2011 at 4:39

Mahesh

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Drooling_Sheep · Accepted Answer · 2011-03-22 04:41:52Z

2

You can use dynamic casting to accomplish this.

e.g.

Base* baseObject = dynamic_cast<Base*>(derivedPtr);

http://www.cplusplus.com/doc/tutorial/typecasting/

answered Mar 22, 2011 at 4:41

Drooling_Sheep

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2 Comments

Xeo Over a year ago

You don't need dynamic cast for this. You only need it for a cast from a Base to Derived. And since the OP wanted a new Base object, you don't need casting at all. :)

Drooling_Sheep Over a year ago

Ah okay, Thanks. I was taught to err on the side of too much casting, so sometimes I forget when it's unnecessary.

Xeo · Accepted Answer · 2011-03-22 04:45:06Z

0

Yes. That's actually called 'slicing', since you just slice off everything from the derived class.

edited Mar 22, 2011 at 4:45

answered Mar 22, 2011 at 4:37

Xeo

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