How to pass a function as an argument to another function in C++?

Question

Hello everyone, I'm trying to pass a function to another function but I'm not sure on how to do that. Here is my code so far:

// Example program
#include <iostream>
#include <string>

struct listNode{
int num;
listNode * next;
};

int numOfNodes(struct listNode firstNode){
int countNodes = 0;
while(firstNode -> next != NULL){
countNodes ++;
}
return countNodes + 1;
}

int middleOfList(struct listNode firstNode,){
//incomplete

What I'm trying to do is pass numOfNodes to middleOfList as an argument. Any answers will appreciated.

Answer 1

https://en.wikipedia.org/wiki/Function_pointer

But I'm not sure a function pointer would be a very wise idea here.
Not something for a beginner to play around with as the syntax can be quite confusing.

Why not just call numOfNodes inside middleOfList?

Answer 2

I honestly wasn't thinking of that. I'm going to do that then, Thank you