inheritance and headers

[Ceset]

guys i remember i have read that inheritance slows down the process.

because
a_class -> b_class -> c_class ...
it goes thorough many classes to find a function or a value. people advices not to do it more than a few times. correct me if i m wrong pls

and also there is something that we call using headers. what if instead of inheritance we are using headers, would it slow down the process also??

i mean which one is faster? and arent both the same when we use headers or used inheritance. both does same(???do they) a class calls another

i believe i do not totally understand both yet.

[Daleth]

Headers and inheritance don't have anything to do with one another.

//Inheritance
class Base{};
class Derived : public Base{};

//Headers
//MyHeader.h
#ifndef MYHEADER_H
#define MYHEADER_H
int funky();
struct boy_oh_boy{
   int I;
};
#endif

//MySource.cpp
#include "MyHeader.h"
int funky(){return 34;}

//main.cpp
#include "MyHeader.h"
#include <iostream>

int main(){
   boy_oh_boy bob;
   bob.i = 55;
   std::cout << funky() << '\n' << bob.i << std::endl;
   return 0;
}

I don't know if inheriting for the 100th time would really affect performance that much. The only slowdown I know of is from the vtable, which increases overhead cost.
You can look at the inheritance tree of iostream's classes and see that they make heavy use of inheritance.

[AbstractionAnon]

When using inheiritance with virtual functions, there is a table of pointers to the virtual functions (vtable) for each class. When calling a virtual funtion, the call is made through the pointer in the vtable. The cost to call a function through a pointer is insignificant.

I don't understand your question about headers. Are you referring to header files?
Header files do not contain executable code, so there is nothing to slow down.

[Ceset]

maybe i should just forget about my questions other than "does inheritance slow down the process".
i believe i will be able to ask a more proper question in time