User forums > General (but related to Code::Blocks)

do I understand C++ wrong?

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MoonKid:
It is a simple problem.

The compiler (mingw32) says
[error]
main.cpp:27: error: no matching function for call to `ClassB::Function()'
main.cpp:17: note: candidates are: bool ClassB::Function(const char*)
[/error]



--- Code: ---#include <iostream>

class ClassA
{
    public:
        bool Function ()
        {
            return true;
        }
};


class ClassB : public ClassA
{
    public:
        bool Function (const char* str)
        {
            return true;
        }
};


int main()
{
ClassB b;

b.Function();

return 0;
}

--- End code ---

I do not understand the compilers problem.
Because A::Function and B:Function has different names because the
signaturs (name+parameters) are different.
Shouldn't it work in iso-c++? Is it a compiler problem or I am wrong
understanding standard c++?

PChris:
You have to pass the parameter as well ;)
e.g: Function("Hello");

MoonKid:

--- Quote from: PChris on April 22, 2006, 02:15:58 pm ---You have to pass the parameter as well ;)
e.g: Function("Hello");

--- End quote ---

No, I do not want to call ClassB::Function. I want to call ClassA::Function. I think the compiler should know that because of the signature.

I know I could call it like that
b.ClassA::Function()

But the compiler should know it by itsefl.

PChris:
I don't really understand you...
If there is a function in ClassB, why should the compiler search the function in ClassA?

MoonKid:

--- Quote from: PChris on April 22, 2006, 02:35:49 pm ---If there is a function in ClassB, why should the compiler search the function in ClassA?

--- End quote ---

The compiler generates symbols (names) for functions while compiletime.

"bool ClassA::Function()" is a different name instead of "bool ClassB::Function(const char*)".
Not because of A and B. Because of the signature of the methodes.
A methode name is generated on functionname+parameters, that is what is called "signature of a function".

That is what I have learned about compilers.

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