overriding

This doesn't work: class Foo { public: virtual int A(int); virtual int A(int,int); }; class Bar : public Foo { public: virtual int A(int); }; Bar b; int main() { b.A(0,0); } It seems that by overriding Foo::A(int) with Bar::A(int) I have somehow hidden Foo::A(int,int) . If I add a Bar::A(int,int) things work. Does anyone have a link to a good description of what's going on here? CB Bailey Essentially, name lookup happens before overload resolution so the function A in your derived class overrides the virtual function in the base class but hides all other functions with the same name in any

I'm trying to understand how Java handles cases of ambiguity that come out when a concrete class inherits (abstract or concrete) methods having the same name from different classes/interfaces. I've not been able to find a general rule, this is why I decided, once for all, to spend some time on this by using a practical approach. I considered 8 different cases, combining abstract methods non-abstract methods abstract classes interfaces resulting in this scheme: +-------------------------+ | INTERFACE | +----------+--------------| | abstract | non-abstract | | method | method | +-----------+----

I have a base class which I want to provide some 'base' functionality for methods for all inheriting classes. In my inheriting classes I want to do: public override void Setup() { base.Setup(); } But at the moment it says I have to use the new keyword. How to I have it so I have to use the override keyword? Is there any difference between how it is currently with me using the new keyword and using override ? It says so because you have not declared the base method virtual . Once you do so, the base virtual /derived override pair of keywords will make sense. Right now, the compiler is

Is it possible to overload operators (such as operators of comparison) in C? If so, how do you do it? I did a quick search, but all I found was for C++, and what I want is for C. Anyone have any ideas? Edit1: The idea is: I have a struct, and I need to do a comparison (based on a member of the struct). And for this I would like to associate operators compared to my new "data type". Edit2: I am completely aware that I can do without the use of operator overloading, but was wondering if you can do this WITH OVERLOAD. Answer: The concept of overload is associated with object-oriented programming.

I have a class, show below, which is used as a key in a Dictionary<ValuesAandB, string> I'm having issues when trying to find any key within this dictionary, it never finds it at all. As you can see, I have overridden Equals and GetHashCode . To look for the key I'm using ValuesAandB key = new ValuesAandB(A,B); if (DictionaryName.ContainsKey(key)) { ... } Is there anything else that I'm missing? Can anyone point out what I'm doing wrong? private class ValuesAandB { public string valueA; public string valueB; // Constructor public ValuesAandB (string valueAIn, string valueBIn) { valueA =

This is a question just out of curiosity. I know that when we call a subclass object's overridden method by the reference of it's superclass, JVM gives importance to the type of object and not to type of reference. This is my simple code : class Animal { void eat() { System.out.println("Animal is eating..."); } } class Horse extends Animal { @Override void eat() { System.out.println("Horse is eating..."); } } public class PolymorphismTest { public static void main(String...args) { Animal a=new Animal(); a.eat(); Animal h= new Horse(); h.eat(); } } As expected, I get the output : run: Animal is

A virtual function's return type should be the same type that is in base class, or covariant. But why do we have this restriction? Because of the nonsense that would ensue: struct foo { virtual int get() const { return 0; } }; struct bar : foo { std::string get() const { return "this certainly isn't an int"; } }; int main() { bar b; foo* f = &b; int result = f->get(); // int, right? ...right? } It isn't sensible to have a derived class return something completely unrelated. Because how would the code that's using the return value cope with all sorts of unrelated types coming back? e.g.: class

Possible Duplicate: Is there any way in C# to override a class method with an extension method? Is it possible to override or shadow ( new in C#) instance methods with extension methods? No. From MSDN : You can use extension methods to extend a class or interface, but not to override them. An extension method with the same name and signature as an interface or class method will never be called. At compile time, extension methods always have lower priority than instance methods defined in the type itself. 来源： https://stackoverflow.com/questions/1745166/override-or-shadow-a-method-with-extension

I have a style assigned for a specific HTML element in my stylesheet file, like this label { width: 200px; color: red; } In one special case, I would like to use a label element in the HTML document, but ignore the style specified for the label element (just for one instance in the document). Is there any way to achieve this in a generic way without overriding the element style attributes with inline styles ? <label for="status">Open</label> To reiterate, to the HTML code displaying the label the element style (width 200 px, color red) is applied. I would like the default style attributes to