Now, let's talk about a more practical example and relate it to the pizza example.

There is a function in the <cmath> library called the sqrt() function. Let me quickly illustrate its use, as shown in the following code:

#include <iostream>
#include <cmath>
using namespace std;
int main()
{
  double rootOf5 = sqrt( 5 ); // function call to the sqrt  function
  cout << rootOf5  << endl;
}

So, sqrt() can find the mathematical square root of any number given to it.

Do you know how to find the square root of a tough number such as 5? It's not simple. A clever soul sat down and wrote a function that can find the square roots of all types of numbers. Do you have to understand the math behind how the square root of 5 is found to use the sqrt(5) function call? Heck, no! So, just as the waiter didn't have to understand how to cook a pizza in order to get a pizza as the result, the caller of a C++ library function does...