derived-class

After asking the question Call a method that requires a derived class instance typed as base class in VB.NET or C# on Stack Overflow, I was informed that I had used the wrong terms when asking the question. I had used "parent" and "child" where I should have used "base" and "derived" instead. I have been unable to find a good description of the difference. This is what I know (or think I know) so far: A parent class contains the child class. Where as a derived class inherits from a base class. They are similar because the child (or derived) can access the parents (or base) properties and

I don't know if this is possible, but I am trying to get the Base Class instance from a Derived Class. In C#, I can use the base keyword to access properties and methods of the Base Class (of course), but I want to use base itself. Attempting to do so results in a "Use of keyword 'base' is not valid in this context" error. Example Code public class SuperParent { public int SPID; public SuperParent() { } } public class SubChild : SuperParent { public SubChild(int pSPID) { base.SPID = pSPID; } public int BaseSPID { get { SuperParent sp = base; return sp.SPID; } } } If you're working with an

I have been a .Net coder (can not say I am a programmer) for 2 years. There is one question that I can not understand for years, that is how could an instance of the base class hold an instance of the derived class? Suppose we have two classes: class BaseClass { public A propertyA; public B propertyB; } class DerivedClass ：BaseClass { public C propertyC; } How could this happen: BaseClass obj = new DerivedClass () I mean, the memory model of BaseClass , has no space for the newly added propertyC, so how could it still hold the value of propertyC? On the other side, how could this can not

I have the following base class: class NeuralNetworkBase: def __init__(self, numberOfInputs, numberOfHiddenNeurons, numberOfOutputs): self.inputLayer = numpy.zeros(shape = (numberOfInputs)) self.hiddenLayer = numpy.zeros(shape = (numberOfHiddenNeurons)) self.outputLayer = numpy.zeros(shape = (numberOfOutputs)) self.hiddenLayerWeights = numpy.zeros(shape = (numberOfInputs, numberOfHiddenNeurons)) self.outputLayerWeights = numpy.zeros(shape = (numberOfHiddenNeurons, numberOfOutputs)) now, I have a derived class with the following code: class NeuralNetworkBackPropagation(NeuralNetworkBase): def _

I am new to c++. When I try to compile the code below , I get this error constructor for 'child' must explicitly initialize the base class 'parent' which does not have a default constructor child::child(int a) { here is my class #include<iostream> using namespace std; class Parent { public : int x; Parent(int a); int getX(); }; Parent::Parent(int a) { x = a; } int Parent::getX() { return x; } class Child : public Parent { public: Child(int a); }; Child::Child(int a) { x = a; } int main(int n , char *argv[]) { } Why I am getting this error ? How can I resolve it ? Thanks in advance The parent

When a method is declared as virtual in a class, its overrides in derived classes are automatically considered virtual as well, and the C++ language makes this keyword virtual optional in this case: class Base { virtual void f(); }; class Derived : public Base { void f(); // 'virtual' is optional but implied. }; My question is: What is the rationale for making virtual optional? I know that it is not absolutely necessary for the compiler to be told that, but I would think that developers would benefit if such a constraint was enforced by the compiler. E.g., sometimes when I read others' code I

I have a virtual base class function which should never be used in a particular derived class. Is there a way to 'delete' it? I can of course just give it an empty definition but I would rather make its attempted use throw a compile-time error. The C++11 delete specifier seems like what I would want, but class B { virtual void f(); }; class D : public B { virtual void f() = delete; //Error }; won't compile; gcc, at least, explicitly won't let me delete a function that has a non-deleted base version. Is there another way to get the same functionality? It is not allowed by the standard, however