I've created a base DLL for all my future DLL's, a way of getting version numbers and such and that compiles fine, but I can't add it into a class for a new DLL. All the headers do have an appropriate cpp to define the function declarations (and they compile fine).
As long as no base class constructor takes any arguments, the derived class need not have any constructor, if one or more arguments are used then it is mandatory for the derived class to have a constructor and pass the arguments to base class constructors. While applying inheritance, we usually create objects using derived class. Then it makes sense for the derived class to pass arguments to the base class constructor. When both the base and derived class contain constructors ,the base class constructor is execute first.
In case of multiple inheritance, the base classes are constructed ,in the order in which they appear in the declaration of the derived class. Similarly in a multiple inheritance the constructors will be executed in order of inheritance. Since the derived class takes the responsibility to supply initial values to the base class,we supply the initial values that are required by all the classes together where the derived class object is declared.
The constructor of the derived class receives the entire list of values of arguments and pass them on to the base constructors int the order in which they are declared in the derived class
Is it possible to overload a variable in a derived class? Example:
struct Circle { int radius() const { return r; } private: int r; } struct Smiley : Circle { // inherits the function int radius() const, but doesn't return Smiley::r private: int r; }
class Var { public: Var(); ~Var(); private: QMap<QString, QSharedPointer<Data>> _mapVars; }; QDataStream &operator<<(QDataStream &stream, const QSharedPointer<Data> p_data); QDataStream &operator>>(QDataStream &stream, Data &p_data)
I want to serialize _mapVars into a file. However, I have many other classes that are derived from Data, do i need to check for Data type inside the overloaded << functions like below in order to serialize ??? This doesn';t seem to be very correct ...
S I want to have different >> operators for several derived classes. Has I tested...
Code: class base{ friend std::istream & operator>>(std::istream & in, base & v); public: base();
[Code]......
I noticed that the base operator is the only one being called for all 3 objects. which makes sense and now that I think about it I am more surprised that the "derived operators" compiled at all.
Still, how would I go about declaring different overloaded operators for the different classes?
main3.cpp: In member function ‘FooB& FooB::operator=(const FooC&)’: main3.cpp:46:44: error: expected ‘(’ before ‘other’ main3.cpp:46:49: error: no matching function for call to ‘Foo<C>::Foo(const FooC&)’ main3.cpp:46:49: note: candidates are: main3.cpp:19:2: note: Foo<T>::Foo() [with T = C] main3.cpp:19:2: note: candidate expects 0 arguments, 1 provided main3.cpp:16:25: note: Foo<C>::Foo(const Foo<C>&) main3.cpp:16:25: note: no known conversion for argument 1 from ‘const FooC’ to ‘const Foo<C>&’
I need to access the functions of the derived classes from a vector of objects of base classes (can't believe I wrote it). Here a Diagram for you to understand:
So as you see, I need the function Use() from the Usable class, to be able to be called from the vector like:
I have an array of (Student)classes created in Manager.h, which contains a new instance of class Name (name),(in Student.h)How would I go about accessing the SetFirstName method in Name.cpp if I was in a class Manager.cpp? I have tried using Students[i].name.SetFirstName("name");
// In Manager.h #include"Student.h" class Manager {
I'm trying to call a function on a derived class that's in a vector of it's base class. I've made the code really simple for illustration purposes:
class Sprite { virtual void update(); } class Enemy : public Sprite { virtual void update();
[Code] ....
I want to be able to just call update() on the items in the vector and the derived class update() functions be called. Currently, it always calls the Sprite update, which makes sense, but it's not what I want. Is there a way to call the derived update function without knowing the type of the derived class?
The place where I should put the return value is marked with ???. SEntityPhysicalizeParams is a struct from another header from which I dont have access to it's source file.
I tried several things but noone seemed to work out and keep getting me either error "function must return a value" or "initial value of reference to non-const must be an lValue".
Here is SEntityPhysicalize where my function is refering to:
I have a big problem with searching a solution for getting access on getters and setters of the derived classes of an interface.
Interface:
class IfParam { public: IfParam(); };
Now I have a derived class for each needed datatype. E.g.
class Int32Param: public IfParam { public: Int32Param(); Int32Param(IfParam* l_param); int getValue(); void setValue(int l_value); private:
[Code]...
My Problem now ist getting access to the getters/setters over the interface. I wish I could initialize the Params like this:
IfParam* param = new Int32Param(); param.setValue(12);
IfParam* param = new StringParam(); param.setValue("String");
But to have access to the getter/setter I have to declaire the functions in the interface as generic functions. But how? I tried to use temlates, but then i have to declaire IfParam as IfParam<int>. Thats a problem because in my original program I do not know which TypeParam the IfParam interface will be initialized with when I create the pointer.
I don't understand why my compiler gives me this error when I'm trying to run this code:
Code:
#include <iostream> #include <cmath> using namespace std; class Airplane { public: Airplane(); ~Airplane();
[Code]...
The variable is protected. Yeah, that's right. But shouldn't a derived class be able to reach it? Or is it only in a function that the derived class is able to reach protected variables and isn't able to reach protected variables in the constructor?
Is is possible to force derived classed to overload certain operators, like we do with pure virtual functions?
Is this possible to dynamically bind objects to their respective overloaded operators?
I am getting errors with undefined references to my base class vtable when I hackly try to overload: Code: operator+ I am not sure whether this is possible.
I would like to access (use) a (virtual) method declared in a base class via a pointer to an object belonging to a derived class, which overrides the base method. Is it possible? Up to now I have not been successful. I am including a program with a more detailed description.
// declare a base class T0 with virtual function P, and a derived // class T1 which overrides P; declare two ptrs, to T0 and T1, // and generate corresponding objects; calling P via the two // ptrs gives expected result; however I would like to take // ptr to T1 object & execute the base function (declared // in T0); is it possible? I tried all possible casts but nothing // works; no matter how I cast the pt1 ptr, I always end up executing // the overriding function (declared in T1) // actual output (debian 7, gcc 4.7.2-5):
I have base class with some properties(variables).I want to inherit that class and want to change name of that properties in the derived class using concept of Shadowing.
I need to create an object of a mfc derived CFormView class that's not in the doc/template (a second view class). But it was generated with a protected ctor. Here's the code explanation with comments.
I'm thinking all the normal classes of the Doc/View template are created starting with this code, but within the template code base.
Code:
CSingleDocTemplate* pDocTemplate; pDocTemplate = new CSingleDocTemplate(IDR_MAINFRAME, RUNTIME_CLASS(CViewSwitchDoc), //<-expands to-> ((CRuntimeClass*)(&CViewSwitchDoc::classCViewSwitchDoc)), RUNTIME_CLASS(CMainFrame), // main SDI frame window RUNTIME_CLASS(CViewSwitchView));
But I have generated "another view" using the "Add Class" Wizard, it's a derived class of mfc CFormView which I named ViewForm. However I'm having a problem creating an instance of it because of the generated protected ctor and pulls a compile error of not being able to access ctor. Below are the header and implementation files of this said ViewForm class. How to create an object of this view ? Did I go about it all the wrong way since it's not in the doc/template group ?
// ViewForm.h file #pragma once // ViewForm form view class ViewForm : public CFormView { DECLARE_DYNCREATE(ViewForm)
Is there a way to copy a derived class object thru a pointer to base?
For example:
class Base { public: Base( int x ) : x( x ) {} private: int x; }; class Derived1 : public Base { public: Derived( int z, float f ) : Base( z ), f( f ) {} private: float f;}; class Derived2 : public Base { public: Derived( int z, string f ) : Base( z ), f( f ) {}
[Code] ....
The question is whether *B[0] would be a Derived1 object and *B[1] a Derived2 object?If not, how could I copy a derived class thru a pointer to the base class?
I'm trying to write a function for receiving messages, so my classes can communicate with each other. The only issue I get is a compile error asking me to define the base parameter as one of the derived instances. I tried using a void* to fill the need, but then I lose the initial type, which I need to check for. How might I go about writing a generic object for this?
Here's my code:
template<class Object> class State { public:
[Code].....
Should I just have all of the objects inherit in the order of Object >> GenericObject >> DerivedObject?
I have a very similar dialog called IDD_SETTINGS2_DIALOG with all the exact same variables. Is it possible to conditionally load either of those dialogs in that class through a variable pass into the constructor? If so, how do I edit that enum type to add both?
