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--- notes:data:fall2024:classnotes [2024/08/29 19:00] – gsalce
+++ notes:data:fall2024:classnotes [2024/09/10 17:46] (current) – [Class Notes 9/5 Data / Discrete] gsalce
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 ====Class Notes 8/27 Data/Discrete====
-Preamble:
+===Preamble:===
 --------
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 -Journals / Class documents available
-Class Discussion:
+===Class Discussion:===
 ----------------
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 ====Class Notes 8/29 Data / Discrete====
-Preamble:
+===Preamble:===
 --------
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-Class Discussion:
+===Class Discussion:===
 ----------------
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 -Next time we will discuss linked lists for msi1.
+====Class Notes 9/3 Data / Discrete====
+===Preamble:===
+--------
+-btt0 is coming due tomorrow. msi0 is for next Wednesday
+-msi1 and msi2 are made available. After 0, we are going to switch over to using data structures. The first to explore is singly-linked lists. The idea is to take the array-based msi0 and update it to linked list stuff. Both msi1/2 are related to singly-linked lists. After 2, the project will involve double-linked lists, an evolution of space invaders maybe.
+===Class Discussion:===
+----------------
+-We talk about HOW to do linked lists.
+-First, we know an array has an allocated, fixed amount of space, filled with elements. Can't use more or deallocate less. Big use in C to know how much space we needed exactly. Now that we get into deeper programming, we could have scenarios where we don't know up front how much space exactly we will need. Arrays become impractical "do we need 7 or 17? etc..." In many cases, we cannot declare an array with, per se, one-million entries. In C, we can work around this using pointers and malloc, but still, an amount must be declared up front. Again, arrays can be impractical.
+-The first data structure is what is known as a "linked list". When you start with a list, that list is empty / NULL. When you need a node, you make a node. The first would point to the node, then the node would point to the end, being NULL. If you add more, the node's can point to each other and then to the end eventually. This is nice because you can give / take as many data nodes as you wish / need. The drawback is that arrays can lookup the memory easier. Such is the exchange: conveniance of use vs conveniance of lookups.
+-NOT EVERY NODE IS ONE AFTER THE OTHER, ONE NODE DOES POINT TO ANOTHER, BUT AWARENESS OF CONNECTIVITY IS REQUIRED.
+-You want to make a node, ideally a struct, and in the struct is the data the node will have. Nodes are the foundation of a linked list.
+*In this class, we will explore only a few kinds data structures. There exist many to this day.
+*The times, they are a'changin'.
+-Nodes need to have a pointer. For singly-linked lists, the nodes need to at least have a "[STRUCT NAME] *next" in vircon bc there is no typedef. "next" comes highly recommended. For msi0, you are probably storing X/Y, alive status etc. These will also need to be in the pointer struct.
+-Another thing that comes recommended is a tmp node pointer called tmp. This looks like:
+	Node *tmp 	= NULL
+	tmp		= (Node *)malloc(sizeof(Node));
+-After creating a node, we want to make sure the next points to NULL. This is the node creation operation.
+-You will also want to create a list to chain the nodes together thru appending, obtaining, and maybe inserting.
+-Ideally, it would help to have a pointer fixed in place, something like:
+	Node *start	= NULL;
+-Notice how in a singly-linked list, we can only go forawrd, but not back.
+-Avoid using "for" loops, because you can't know how many there are in the list forever. Consider conditional processing like "while" loops.
+-msi1: take out the array functionality, replace it with linked lists.
+-msi2: making many more functions, replacing single linked lists to double linked lists.
+====Class Notes 9/5 Data / Discrete====
+===Preamble:===
+--------
+-Interesting: Now both Ken and Xavier are missing...
+-Lamenting the failures of The Acolyte.
+-Discussed past projects that were due yesterday, mainly btt0.
+===Class Discussion:===
+----------------
+-Worked on projects
+====Class Notes 9/10 Data/Discrete====
+===Preamble:===
+--------
+-Class saved from the 15 minute rule by 40 seconds
+-Next week's project is still the same for data and discrete. After next week's project, things will pivoting.
+-Discrete's first branch project will be dsr0, "Discrete Skills Review".
+-After that, will be pnc0, "Prime Number Calculator". This will be the same as the comporg project, minus the assembly.
+-As part of msi2, there may be the availability to submit msi2 for 1 and 2 pending understanding of concepts.
+-For msi3, the singly linked list becomes a doubly linked list. Where previously there was only "->next", there will also be a "->prev" and will help tremendously with certain functions like insert() for example.
+-Also msi3, expand the game to be something MORE than just Space Invaders, closer to Galaga. Have extra powerups, enemy movement, etc
+===Class Discussion:===
+----------------
+-Looked at msi2 projects page. The functions will be instrumental in not only this project, but the many to come. They are the foundation for future learnings.
+	Example 1 (calling functions):
+	List *rmlist( List * ); // The function exists
+	mylist = rmlist( mylist ); // The function is called
+	mylist = obtain( mylist, &tmp ); // passing pointer by address
+-When you need to make a list, use mklist().
+-To make nodes, use mknode().
+-To add nodes, use append() / insert().
+-At the end of the process, use clearlist() and rmlist().

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