I am facing some problems while overloading base class functoin in child class. I have 2 programs as listed below.
Program 1 :
#include <iostream>
using namespace std;
class base
{
[Code].....
Compilation Errors:
child_overload.cpp: In function "int main()":
child_overload.cpp:27: error: no matching function for call to "child::func(const char [16])"
child_overload.cpp:17: note: candidates are: void child::func(double)
I thought as base class members are also as part of child class through "public" access specifier, it should access base class function, when funct() is called with a string. if I use "using base::func" in child, it works fine. But why I need that when base class memebers are part of child class?
I am facing a real-life problem, it can be simplified as below:
#include <iostream> using namespace std; class B; class A { public: void f1(A a) {} void f2(B b) {}
[Code]...
There is no problem at all with the f1(), it compiles and executes without any problem. But f2() gives compilation error. How to solve this?
The error message is: error: 'b' has incomplete type This is just to define the function f2() in a class, that uses an instance of its child class as one of its arguments.
I am currently having an issue with a piece of code that I am writing in which I need to use a vector of a child class as a parameter in a function in the parent class. Below is an example of my code:
#include "child.h" #include <vector> class parent { parent(); function(std::vector<child> children); // rest of class here }
When I do this my program doesn't compile. However if I try to forward declare, as shown in the following example, it once again refuses to compile:
#include <vector> class child; class parent{ parent(); function(std::vector<child> children); // rest of class here }
This time, it refuses to compile because it needs to know the full size of the class child in order to create the vector. How to being able to access the child is essential for my program, so what should I do?
We want a solution in C++ that must be able to do the following:
Given a string of particular type, lets say 'A', we want to find all the types that derives from 'A'.
Instantiate new objects out of the types that are derived from 'A'.
E.g. Lets say we have a class, VehicleEntity. VehicleEntityhas child classes, PassangerCarEntity, TruckEntity, TrainEntity, BoatEntity.
We are unsure what vehicle entities there may be as the a library could be added containing more VehicleEntities. E.g. an AirplaneEntity thaterives from VehicleEntity could be added after deployment.
In the application, when a user wants to select a VehicleEntity, the user should be able to pick any of the entities deriving from VehicleEntity. This includes the PassangerCarEntity, TruckEntity, TrainEntity, BoatEntity and AirplaneEntity. The user selects an Entity, lets say AirplaneEntity, A new object of type AirplaneEntity must be instantiated.
The following is an concept example in C# of what we want to achieve in C++.
In C# the items for the dropdown list can be retrieved as follows:
Type vehicleEntityType = typeof(VehicleEntity); List<Type> types = new List<Type>(); foreach (Assembly assembly in AppDomain.CurrentDomain.GetAssemblies())
[Code] .....
We are aware that standard C++ does not contain any Metadata on its objects, and thus it is not possible without a workaround. It does not seem possible with RTTI and boost.Mirror.
I need a2 to be a deep copy of a1, but if I understand it correctly, then a2 should just be a pointer copy of a1. How do I make a2 be a different instance of B?
I am making a very basic parent/child class based program that shows polymorphism. It does not compile due to a few syntax errors reading "function call missing argument list. Lines 76 and 77, 81 and 82, and 86 and 87.
#include<iostream> using namespace std; class people { public: virtual void height(double h) = 0; virtual void weight(double w) = 0;
The abstract class can provide more functionality without affecting child classes.If we add any method to the interface ,then will it affect all the child classes ?
So i am having troubles with operator overloading in inherited class. Basically, it doesnt work. Consider this:
Code:
class A { public: A() { x=0; z= new int;
[Code] ....
Some how the copy constructor of a is improperly executed - the pointer is copied over, not re-created. As a result, the destructors crashes due to double-free.
*/ B bb = b; //doesnt work B bbb(b); //doesnt work B bbbb(b, 0); //works }
Above code shows the problem well. The "official" copy-constructor wont work - it copies over the pointer directly, and doesnt create a new one as it should. However, if i provide my own pseudo-copy-constructor that works. But ofcourse it's just a cheap work around - and wont actually work in real code (STL).
I am stucked in a problem of overloading arithmetic operators such as "+,*" for a class in the form
class Point { int N; // dimension of the point double *Pos; // length of N }
My assign operator is : Point& Point::operator= (const Point& pt) { N= pt.N; if(Pos == NULL) Pos = new double[N]; memcpy(Pos, pt.Pos, N*sizeof(double));
[Code] ....
The add operator "+" is: Point operator+( const Point& pt1, const Point& pt2 ) { Point ptr = Point(pt); // this is a constructor for (int i=0; i<pt1.N; i++) ptr.Pos[i] += pt2.Pos[i]; return ptr; }
Based on the above overloading, What I am going to do is :
P = alpha*P1 + beta*P2; // alpha and beta are double constants, P1 and P2 are Points objes
It is ok with Intel C++ 14.0 compiler, but does not work with the microsoft visual c++ 2012 compiler in debug mode in visual studio 2012.
I stepped in those operators and found that visual c++ compiler deconstructs the ptr in operators "*" and "+" before its return while intel c++ finished the operation P = alpha*P1 + beta*P2; and delete those ptrs at last.
Portability of my operator overloading is worse. How to get those arithmetic operators overloading for class with pointers in it.
The objective is to build a month class that hold data on the number of the month and the name of the month. Using constructors and overloads, set it up to where you can input either the month or the name and it will output the results for both the month number and name.
Here is the code I have so far:
#include<iostream> #include<string> using namespace std; class Month{ private: string name; int monthNumber;
[Code] ....
It is almost fully compiled if I go by the error list. The only problems I see to be having are with the prefix and postfix overloads.
I am creating a class called time and we've had to do operator overloading for <, > , <=, >=, ==, !=, ++, --, >>, <<, * , +, and -.
Well I have done and error checked them all. The only one I cannot seem to get right is the minus and its because of the error checking. I am having issues with times like this
t1 = 0:0:2:3 t2 = 0:0:1:4
t1 - t2 should equal 0:0:0:59 but it returns 0:0:1:-1. (days:hours:minutes:seconds)
I need it to check for all cases and I just do not know how. Here is the code I have so far:
I am having a issues with an assignment in my class and don't really understand why. I am getting undeclared identifier errors even though I have declared and I am also getting an error. Here is the code:
Last time I came to you all with an error it was a simple brain fart on my part but I don't think this one is like that. I would love to tell you what the program is supposed to do but I still do not really know, which might be part of the problem. I guess it outputs different sized rectangles...
I wrote a simple Complex Class and overload input/output and +/- Operators in it!But there is something that doesn't work correctly!I can print an object of that class but I can't print sum of two object or something like that!
I am making a program with a Cartesian class. I want the user to be able to input 2 coordinates, but when I run it it doesn't ask for any values to be entered. It gives this output Please enter the first coordinates: Please enter the second coordinates:
I have been asked to create a program to overload a function which should accept and print first one integer and then two integers. Here is the code i have produced so far: [URL] ....
Code: #include <iostream> using namespace std;
//Overloading f1 three ways
int f1(int a); double f1(double a); long f1(long a);
[Code] .....
I am aware the code should work. my only concern is the error i receive on line 12. I am certain there should be a value in the bracket but i dont know what.
I stumbled upon an unexpected difference between GCC and VisualStudio: Different overloaded functions are called in the following example:
// -------- can assume this is located in 'tool.h' file -------------- // Fwd declaration support foo( const int& ) gets called as expected by both compilers // void foo( const int& n );
template< typename T > void foo( const T& n ) {
[Code] ....
What happens: I expected that by calling bar(1) compiler will notice both versions of foo() and call the best match, in this case foo(const int&). That is not the case.
Note that overloaded foo(const int&) is below bar(). It seems that at that point GCC does not see overloaded version, and happily calls template version. Visual studio on the other hand has no problem finding them both.
If I introduce a forward declaration of foo( const int& ) before bar(), both compilers call that version correctly. Unfortunately, that is not a solution for my problem here.
Template version is part of a library while overloaded is part of the user code. Both would be located in different (header) files and I would not like to impose #include order to the users or to be dependant on it.
Code: class VAR_EXPORT VAR { public: }; VAR_EXPORT QDataStream &operator>>(QDataStream &p_stream, QSharedPointer<Data>& p_data)
[Code] ....
Above compile and build ok. But when i build another library that use the above, i was shown with all errors complaining operator << and >> definition of dllimport function not allowed
error C2491: 'operator >>' : definition of dllimport function not allowed error C2491: 'operator <<' : definition of dllimport function not allowed
