Questions tagged [derived]
429 questions
3
votes
1 answer
Getting a pointer to a (pure) virtual function from a base class instance
I have the following c++11 code, which works, while I would have expected it to crash or even not to compile. Retrieving a pointer to a pure virtual member function should return a null or invalid pointer, or should be blocked by the compiler. I…
galinette
- 8,896
- 2
- 36
- 87
3
votes
1 answer
SQL count how many duplicated values of a derived table
I know this gets asked a lot but no other solution worked for me.
I have this query:
SELECT
us.id AS idUser, ut.id AS idUtente, us.nome AS nomefunc
FROM
utentes ut
JOIN
historico h ON h.idUtente = ut.id
JOIN
users us ON…
xickoh
- 304
- 3
- 10
3
votes
2 answers
How do you set a string data member from a base class, with a derived classed?
I have figured out most of the code/assignment, here is part of the "To-Do" I can't figure out:
The derived classes set the m_type, but note, there is no setType function to do
so (and you can't add one).
Here is my code (nothing in main can be…
Hanna369
- 61
- 5
3
votes
4 answers
Template method over non-template method in derived class
class A {
public:
template void func(size_t n, T values[]) { ... }
};
class B : public A {
public:
void func(size_t n, uint32_t values[]) { ... }
};
Why does function B::func() not take precedence over the function template…
mnn
- 1,952
- 4
- 28
- 51
3
votes
5 answers
Calling base method from derived class
I have, for example, such class:
class Base
{
public: void SomeFunc() { std::cout << "la-la-la\n"; }
};
I derive new one from it:
class Child : public Base
{
void SomeFunc()
{
// Call somehow code from base class
std::cout <<…
Max Frai
- 61,946
- 78
- 197
- 306
3
votes
1 answer
Storing derived classes in a base class Dictionary
I am trying to create a scene or state manager which stores a Dictionary for each state as a way to load or change the state of the program (for example, a Main Menu state and a Game state). I have a bunch of derived classes of base class State…
Charsmud
- 183
- 1
- 4
- 19
3
votes
1 answer
c++ Derived Class of a class that represents items in a library
The LibraryItemsClass stores the Title and the Due date.
The class has two constructors;
A default constructor that gives the due date a value of 0/0/0
A constructor that accepts the title and gives the due date a value of 0/0/0
The Class has four…
user4864774
- 49
- 6
3
votes
1 answer
access base class field from derived&&subclass
I can't understand why I have access to Base class's field. I have no object of Base class, and private fields are not inherited as I know. When I try to get field "i" of class "SubDerived" with reflection, it cannot find it. please anyone…
Tamazi Bagdavadze
- 85
- 2
- 9
3
votes
2 answers
C++ storing base and derived class objects together
I Have two classes:
First:
class Thing {
public:
int code;
string name;
string description;
int location;
bool canCarry;
Thing(int _code, string _name, string _desc, int _loc, bool _canCarry) {
code = _code;
…
Majak
- 1,543
- 1
- 14
- 28
3
votes
1 answer
Prevent a virtual function bering overloaded twice in a sub-sub-class
I have a base class Base, a somewhat more specialized class SpecializedBase derived from Base, and subclasses of the latter such as Derived.
I implement a virtual function in SpecialisedBase which is pure virtual in Base. How to be sure that this…
galinette
- 8,896
- 2
- 36
- 87
3
votes
1 answer
How can I cast a subset of a dictionary to a type derived from Dictionary<>
To simplify using a specific type of dictionary I have derived a class from the generic Dictionary<> to handle assorted elements derived from a common base class:
//my base class holding a value
public abstract class A{ public int aValue;…
AstaDev
- 149
- 1
- 8
3
votes
1 answer
Java - overridden method not getting called
I'm working on a Java exercise and can't figure out what I am doing wrong. I made a Movie class (with variables: rating, title, movieId and a constant for FEE_AMT) and then extended the class with: Action, Comedy and Drama. These derived classes…
Kirk B
- 551
- 6
- 23
3
votes
2 answers
Converting a string to a decimal value in an SSIS package
I have a flat file that I am importing into SQL Server 2008 using an SSIS package.
The file contains a field with a number, followed by a column with a negative sign when the preceding column value is negative.
For instance:
Price Sign
----- …
user1949225
- 33
- 1
- 1
- 3
3
votes
1 answer
How to make a deep copy of an object which is derived from a List
I have the following classes:
public partial class AuthorizationSetObject
{
public AuthorizationObjectList AuthorizationObjects { get; set; }
}
public partial class AuthorizationObject
{
public string Text { get; set; }
}
public partial…
Marc
- 137
- 3
- 10
3
votes
5 answers
Is there any way to know if the non-pure virtual function has been implemented by the derived class in C++?
I am creating a class which is callback based. I need to give the client a freedom to invoke the callback that he defines. For example, I have a class Base:
class Base
{
...
public:
virtual void OnMsgReceived(const char *msg, char *&response);
…
Leonid
- 31
- 1