Default Copy Constructor

[cppg2009]

Why is it recommended to provide implementation of copy constructor instead of using compiler provided " default copy constructor" ?

This is in reference to create new instance of Class from existing one.

Foo object2 = object1 ;

[helios]

The default copy constructor only copies the values of the class members. This is not a problem for classes such as this:

class A{
    int a;
};

But for classes which use pointers, it sometimes is desirable to also copy the objects those pointers point to. For example:

class B{
    A *a;
	B(){
		this->a=0;
	}
	B(const B &copy){
		*(this->a)=*(copy.a);
	}
};

[cppg2009]

thanks for reply , really appreciates ..
If anyone has more insight or links please post them as well.

[grey127]

Because .....


e.g

if we dont provide copy constructor the compiler automatically made a copy constructor but it will do SHALLOW COPY , if you are using pointers than it will point to the same place , both the original one and the new one ...

Copy constructor helps you too handle it seperately ....

[grey127]

Insted of this we need to do DEEP copy use GOOGLE to see the difference