Classes part 18 - Understanding the vtable (Popular interview question) | Modern Cpp Series Ep. 54

►Lesson Description: In this lesson I show you what exactly the vtable is in C++. The vtable is the data structure which holds information about which member functions to call for an instance of class when the presence of 'virtual' exists in inheritance. Understanding a little bit about this data structure, will also give you some intuition about a small performance cost (i.e. storage for the pointer, and following a pointer to call a function) about virtual functions as well.

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[dhanushs]

Great video. Very neatly explained as always. Thank you.

[jugalshah]

Thank you i waited for this topic for long its crystal clear now.

[tejasbachhav]

kudos for your hardwork. But it's difficult to understand, can you explain again with good diagrams?

[heretoinfinity]

What's the link with the multiple inheritance vtables mentioned at the end?

[grenadier]

If I don't override a base function, is vtable still created for my derived class? Or only the pointer is inherited and points straight to the base vtable? For instance:

class Base {
public:
virtual void swim() {}
}

class Derived: public Base {}

Derived derived;

[kunalkumar-icdc]

virtual pointer and virtual table are part of class. So what is the type of virtual pointer and virtual table?

[antonfernando]

why destuctors have to be virtual and constructors can't be virtual, I was asked this once in an interviews, still not sure I have realize an answer.

[zizicz]

Is that vim please? I need to settle smth

[mouseminer]

Hi, I am strugling with this vtable error. Please help
Below is the arduino code for ePaper display.

#include <GxEPD.h>
#include //2.13" E-paper Module (White/Red/Black)
#include <Fonts/FreeMonoBold18pt7b.h>
#include <GxIO/GxIO_SPI/GxIO_SPI.h>
#include <GxIO/GxIO.h>
GxIO_Class io(SPI, SS, 17, 16);
GxEPD_Class display(io, 16, 4);

void setup() {
}
void loop() {
}

Here is the error below
undefined reference to `vtable for GxIO'

collect2.exe: error: ld returned 1 exit status

exit status 1

Compilation error: exit status 1

[snapman]

Dude, use a slide show or something rather than writing.