Recource Video
Thanks for the youtube channel, The Cherno. This post is basically a note I take to remind me what Function Pointer is about.

Function Pointer is a way to assign pointer to a variable.

Pass a function as a parameter.

The usual way about function

The implementation of a regular function should look like.

#include <iostream>

void HelloWorld(){
    std::cout<< "Hello World!"<<std::endl;
}

int main(){
    HelloWorld();
    std::cin.get();
}

The result should be like

What if we try to use auto key for this function?

then you will see an error at the auto.
That is because what HelloWorld() return is a void.

But what if we do like this. auto function = HelloWorld

then the error disapper.
This is because HelloWorld now return a Function Pointer instead of void.
so if we try to print the variable function in the next line, we will get the pointer of the HelloWorld function.

Due to the implicitly conversion,

1
2
3

auto function = HelloWorld;
//much the same as 
auto function = &HelloWorld;

What Function Pointer is about

Functions are of course just CPU instructions, and they are stored in somewhere in our binary/executable file.

Find the Hello World function inside the CPU instruction and give it a pointer, to remember the location of this function code.

so here we can assign a function to a varible.

But what type is this auto actually?

Here the auto hold the type write like

1	void(*function)()

void(*)() is the type eventually, but since we have to get it a name so it became void(*function)().
It works with any other name.(Like I named it jim here)