C++ class access control

[Pinky]

Can somebody please offer some insight on the differences between private and protected access controls? I have really never dealt with protected, and every definition I see seems to sound just like the definition for private, which I do use often (of course).

thanks!

[dighn]

protected is like private with the exception that protected variables/methods can be accessed by the subclass(s) of the class


[This message has been edited by dighn (edited January 01, 2001).]

[Klashe]

Originally posted by Pinky:
Can somebody please offer some insight on the differences between private and protected access controls? I have really never dealt with protected, and every definition I see seems to sound just like the definition for private, which I do use often (of course).

thanks!

A private member cannot participate in inheritance. Only protected members can.

Example:

Class X:{

Protected:
Int I;
Int J;

Private:
Int L;

Public:
Void get_ij();
Void put_ij();
};

Class Y : public X {

Int k;
Public:
Int get_k;
Void make K;
};


Here class Y has access to I and J in class X because they are protected. But Y does not have access to L, because it is private to class X.

[Klashe]

Originally posted by Klashe:
A private member cannot participate in inheritance. Only protected members can.

Example:

Class X:{

Protected:
Int I;
Int J;

Private:
Int L;

Public:
Void get_ij();
Void put_ij();
};

Class Y : public X {

Int k;
Public:
Int get_k;
Void make K;
};


Here class Y has access to I and J in class X because they are protected. But Y does not have access to L, because it is private to class X.

Oh yeah, and ignore the caps in that last post.

[Pinky]

thank you both!

[Conrad Song]

Originally posted by Pinky:
Can somebody please offer some insight on the differences between private and protected access controls? I have really never dealt with protected, and every definition I see seems to sound just like the definition for private, which I do use often (of course).

thanks!

Member Inheritance
Before | After Inherited as
| Pub Pro Pri
-------+--------------------
Pub | Pub Pro Pri
Pro | Pro Pro Pri
Pri | Not Not Not