1. Templated recursive linked lists
uff da
But first...

2. Women in Computing Ice cream social Thursday at 6pm in Herak Courtyard
The group is for all who are in favor of gender equality in computer science

3. Tutoring

4. Assignment 1
For your first assignment, you will be taking linked list and adapting it to be templated, and to have all functions implemented recursively
This assignment is due a week from today
Let's take a look at the existing code...

5. Assertions
An assertion is a statement that must be true for your code to function correctly
Include the header file <cassert> to have access to assert()
assert() takes a single parameter: a boolean expression that should be true
If the parameter is false, assert() will stop your program, output an error message, and trigger a debugger (if you are running with one)
assert(factorial(1) == 1)
a.out: main.cpp:13: int main(): Assertion `factorial(1) == 1' failed.

6. Using a templated class
Think of templates as telling C++ a recipe to create a class based on a class you're passing as a parameter
Whenever* you're referring to a templated class, you must include what type you're passing to it
Let's look at a TenElementArray class...

7. TenElementArray code #ifndef TENELEMENTARRAY_H
#define TENELEMENTARRAY_H
template<class ArrayType>
class TenElementArray {
public:
    ArrayType data[10];
    void setValue(ArrayType val, int index) {
        data[index] = val;
    }    };
#endif

8. Making a class templated
If you have an existing class, there's a fairly straightforward method to make it templated:
Move member function bodies into the header file
Choose an identifier to use as your template class parameter
Replace datatypes you want to be templated with the parameter name
Change places using the class to specify the template type
For an example, let's look at the homework assignment writeup...

9. Recursion
We need two things to make a recursive solution to a problem:
A base case
Other cases that we can solve in terms of solutions to simpler versions of the problem
Let's look at the factorial function

10. Recursion: factorial introduction
The factorial of a non-negative number n is equal to to all numbers between 1 and that number multiplied together
An iterative solution to this is fairly simple
Give it a shot!

11. Recursion: factorial via recursion
We need two things to make a recursive solution to a problem:
A base case
Other cases that we can solve in terms of solutions to simpler versions of the problem
What is our base case for factorial?
What is our recursive step? (How does factorial(n) relate to the answer to a simpler version of the problem?)

12. Debugging recursion
When you compile your code, use the -Wall and -g flags
If you're on clang++ on macOS or Linux, also use -fsanitize=address
If your program crashes, try running it under a debugger
With gdb:
gdb your-program-name
gdb ./a.out
With lldb:
lldb your-program-name
lldb ./a.out
Then type r<enter> to run your program
If it crashes, type bt<enter> to see what functions were running and where

13. Recursion: helper functions
Sometimes, for the recursive call, we need more information that we need in our public-facing function
In these cases, we write helper functions that perform the recursion
Our publically-accessible will almost immediately return the answer as calculated by the helper function
Let's look at our factorial example again...

14. Factorial with a helper function