overloading

问题 I need to use cmath's abs() function, but Visual Studio says it's overloaded and I can't even use something like this: unsigned a = 5, b = 10, c; c = abs(a-b); I don't know how to use it properly. 回答1: The versions in <cmath> are for floating point types, so there is no unambiguously best match. The overload for integral types are in <cstdlib>, so one of those will yield a good match. If you are using abs on different types, you can use both includes and let overload resolution do its work.

问题 Is it possible to put some restrictions in overloading operators new and delete? My overloaded new is linked in a different file to my test program. The scenario is: if(condition is satisfied) call overloaded new else call the actual new defined in new.h 回答1: There are three ways to provide an operator new. replacing one or more of the four non placement default operators new, providing overload to the default operator new (thus with an additional parameter, those may be called with the

问题 At these given classes [ActiveRecord] public class BaseMoo : ActiveRecordBase [ActiveRecord] public class Foo : BaseMoo { } somewhere in the code i do var fooObj = new Foo(); // do something with fooObj BaseMoo obj = fooObj; here i try to cast var newFooObj = (Foo)obj; // and goes well if i changes the classes to this: [ActiveRecord(Lazy=true)] public class BaseMoo : ActiveRecordBase [ActiveRecord(Lazy=true)] public class Foo : BaseMoo { } making it Lazyest at these lines: var fooObj = new

问题 I have something like this: #include <iostream> class X; class A { public: virtual void bar(X &x); }; class B : public A { public: }; class X { public: void foo(A &a) { std::cout << "foo A" << std::endl; } void foo(B &b) { std::cout << "foo B" << std::endl; } }; void A::bar(X &x) { x.foo(*this); } int main(int argc, char **argv) { X x; B b; b.bar(x); return 0; } Compile it and execute it, you'll have: # ./a.out foo A # I believe this is because object is sliced when cast to A. How can I avoid

问题 I am able to overload the method in webservice, though on access it categorize both methods (same method with diff params) as different operations. What is the advantage? Is there any way I can achieve calling same method from the client side and based on parameters it calls the one I need? 回答1: Operation Overloading is a concept available in Object Oriented programming languages. However, WebServices are not limited to OO platforms. They are message oriented, where the message can be

问题 My question is bit lengthy. Kindly answer it only once you go through the whole problem. I have implemented the Diamond Problem as follows: class Polygon { protected: int sides; public: Polygon() { cout << "Polygon's Default Constructor being called." << endl; } Polygon(int a) { cout << "Polygon's parameterized Constructor being called." << endl; sides = a; } void virtual Draw() { cout << "Polygon being drawn." << endl; } virtual ~Polygon() { cout << "Polygon's Destructor being called." <<

问题 I have a class that gets two template template parameters and overloads a function with an argument that is either the one or the other template template parameter but both times with the same template argument: template<template<typename> class TemplArgA, template<typename> class TemplArgB> class CompileError { public: void func(TemplArgA<int> x) {} void func(TemplArgB<int> x) {} }; I am using VC2010 and get error C2535: 'void CompileError<TemplArgA,TemplArgB>::func(TemplArgA<int>)': member

问题 A very formal question: is this considered an overload? Is removing the template fundamentally different than only overloading on arguments? template<class T> void myFunction(const T& t) {} void myFunction(const double& t) {} Then the follow up question, is it better to follow this approach or to use template specialization, instead of the overload? template<> void myFunction(const double& t) {} 回答1: First of all, according to the standard (start of §13): “When two or more different

问题 There is an exercise "OverloadResolutionOverride" What will be the output of the following code: class Foo { public virtual void Quux(int a) { Console.WriteLine("Foo.Quux(int)"); } } class Bar : Foo { public override void Quux(int a) { Console.WriteLine("Bar.Quux(int)"); } public void Quux(object a) { Console.WriteLine("Bar.Quux(object)"); } } class Baz : Bar { public override void Quux(int a) { Console.WriteLine("Baz.Quux(int)"); } public void Quux<T>(params T[] a) { Console.WriteLine("Baz

问题 Say have an overloaded method called doTask : public class Game { void doTask(Joker joker); void doTask(Batman batman, Robin robin); } I would like to invoke the right method, given the name of the method ( "doTask" ) and an array of parameters whose number and types are not known a priori. Normally, this involves three steps at least: 1. Find the number of the parameters and their types, and make an array Class[] myTypes . 2. Identify the correct overloaded Method , i.e. Method rightMethod =