StackOverflow2013

Note that there are some explanatory texts on larger screens.

plurals

PO
primarykey
Id
3787251
data
AcceptedAnswerId
0
AnswerCount
0
ClosedDate
CommentCount
2
CommunityOwnedDate
CreationDate
2010-09-24T12:57:04.960
FavoriteCount
0
LastActivityDate
2010-09-24T12:57:04.960
LastEditDate
LastEditorUserId
0
OwnerUserId
284881
ParentId
3786878
PostTypeId
2
Score
1
ViewCount
0
LastEditorDisplayName
text
Body
"A" is the answer and here's why... a - The parent operation can be overridden (replaced, in a sense) but cannot be changed. <pre><code>#include <iostream> class A { public: A() {} virtual ~A() {} virtual void foo() { std::cout << "Hi, I'm A" << std::endl; } }; class B : public A { public: B() {} virtual ~B() {} virtual void foo() { std::cout << "Hi, I'm B" << std::endl; } }; int main() { A* a = new B(); a->foo(); return 1; } </code></pre> The code above will print... <blockquote> <pre><code>Hello, I'm B </code></pre> </blockquote> B::foo() overrode A::foo() but did not change it. <hr> b - Yes, a subclass can use the implementation of a method in a parent class. For example, if we change the B::foo() method in the above code to... <pre><code>virtual void foo() { A::foo(); // <--------------------------NOTE the addition of this call std::cout << "Hi, I'm B" << std::endl; } </code></pre> ...the program will print... <blockquote> <pre><code>Hi, I'm A Hi, I'm B </code></pre> </blockquote> <hr> c - The subclass can use public or protected attributes of the parent class but not private attributes. For example: <pre><code>#include <iostream> class A { public: A() : pub(1), pro(2), pri(3) {} virtual ~A() {} virtual void foo() { std::cout << "Hi, I'm A" << std::endl; } int pub; protected: int pro; private: int pri; }; class B : public A { public: B() {} virtual ~B() {} virtual void foo() { std::cout << pub << std::endl; std::cout << pro << std::endl; std::cout << pri << std::endl; // <----COMPILE ERROR } }; int main() { A* a = new B(); a->foo(); return 1; } </code></pre> That code will have a compile error on the line noted above because subclass B is attempting to access a private member of the parent class. There is an exception to this rule if another class is declared to be a friend but you should rarely, if ever, use the friend keyword. <hr> d - Yes, a subclass can have opperations that the parent class does not have. For example: <pre><code>#include <iostream> class A { public: A() {} virtual ~A() {} virtual void foo() { std::cout << "Hi, I'm A" << std::endl; } }; class B : public A { public: B() {} virtual ~B() {} virtual void foo() { std::cout << "Hi, I'm B" << std::endl; } virtual void otherFunc() { std::cout << "I'm a function that my parent class doesn't have." << std::endl; } }; int main() { B b; A& a = b; a.foo(); a.otherFunc(); // <--- COMPILE ERROR b.foo(); b.otherFunc(); // <--- OK return 1; } </code></pre> In the example above, otherFunc() was added to subclass B. Attempting to call it from a reference to an A class will cause a compile error. Calling it on a B class works as expected. <hr> The best way to learn and know for sure is to try these things in a compiler. Try the code above. I tested it in Visual Studio 2008. The examples that aren't explicitly labeled with COMPILE ERROR should work.
Tags
Title
singulars
PostAcceptedAnswerId
1. This table or related slice is empty.
PostParentId
1. POWhich of the following is not allowed according to inheritance usage?
 singulars
 PostTypePostTypeId
 PTQuestion
PostTypePostTypeId
1. PTAnswer
UserLastEditorUserId
1. This table or related slice is empty.
UserOwnerUserId
1. USdgnorton
plurals
PostLinksPostIdRelatedPostId
1. This table or related slice is empty.
PostLinksRelatedPostIdPostId
1. This table or related slice is empty.
PostsAcceptedAnswerId
1. This table or related slice is empty.
PostsParentIdCreationDate
1. This table or related slice is empty.
VotesPostIdCreationDate
1. VO
 singulars
 PostPostId
 PO
 UserUserId
 This table or related slice is empty.
 VoteTypeVoteTypeId
 VTUpMod
CommentsPostId
1. COI think option A "Changing implementation of operation in parent by the subclass" is just poorly worded, making the question ambiguous. A case could be made for either A or E, depending on how you interpret A.
 singulars
 PostPostId
 PO
 UserUserId
 USBill the Lizard
2. COBill the Lizard, you're probably right but I think (read: just my opinion) that someone new to C++ would likely interpret it such that "A" would be correct. I tried to make a distinction between "changing" and "overriding" (replacing) in my answer.
 singulars
 PostPostId
 PO
 UserUserId
 USdgnorton

Querying!

Guidance

A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.