C++ issue with function overloading in an inherited class

cclassinheritanceoverloading

This is possibly a noob question, sorry about that. I faced with a weird issue recently when trying to mess around with some high level stuff in c++, function overloading and inheritance.

I'll show a simple example, just to demonstrate the problem;

There are two classes, classA and classB, as below;

class classA{
    public:
        void func(char[]){};    
};

class classB:public classA{ 
    public:
        void func(int){};
};

According to what i know classB should now posses two func(..) functions, overloaded due to different arguments.

But when trying this in the main method;

int main(){
    int a;
    char b[20];
    classB objB;
    objB.func(a);    //this one is fine
    objB.func(b);    //here's the problem!
    return 0;
}

It gives errors as the method void func(char[]){}; which is in the super class, classA, is not visible int the derived class, classB.

How can I overcome this? isn't this how overloading works in c++? I'm new to c++ but in Java, i know I can make use of something like this.

Though I've already found this thread which asks about a similar issues, I think the two cases are different.

Best Answer

All you need is a using:

class classB:public classA{ 
    public:
        using classA::func;
        void func(int){};
};

It doesn't search the base class for func because it already found one in the derived class. The using statement brings the other overload into the same scope so that it can participate in overload resolution.

Related Solutions

C++ – When should you use a class vs a struct in C++

The differences between a class and a struct in C++ is:

struct members and base classes/structs are public by default.
class members and base classes/struts are private by default.

Both classes and structs can have a mixture of public, protected and private members, can use inheritance and can have member functions.

I would recommend you:

use struct for plain-old-data structures without any class-like features;
use class when you make use of features such as private or protected members, non-default constructors and operators, etc.

Python – Are static class variables possible in Python

Variables declared inside the class definition, but not inside a method are class or static variables:

>>> class MyClass:
...     i = 3
...
>>> MyClass.i
3

As @millerdev points out, this creates a class-level i variable, but this is distinct from any instance-level i variable, so you could have

>>> m = MyClass()
>>> m.i = 4
>>> MyClass.i, m.i
>>> (3, 4)

This is different from C++ and Java, but not so different from C#, where a static member can't be accessed using a reference to an instance.

See what the Python tutorial has to say on the subject of classes and class objects.

@Steve Johnson has already answered regarding static methods, also documented under "Built-in Functions" in the Python Library Reference.

class C:
    @staticmethod
    def f(arg1, arg2, ...): ...

@beidy recommends classmethods over staticmethod, as the method then receives the class type as the first argument, but I'm still a little fuzzy on the advantages of this approach over staticmethod. If you are too, then it probably doesn't matter.

Best Answer

Related Solutions

C++ – When should you use a class vs a struct in C++

Python – Are static class variables possible in Python

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