- List
- Subroutines
- Communication protocols
- Abstract data structure that implements an ordered collection ofvalues, the same value can occur more than once
- The size of the list indicates the number of elements
- Elements can be accessed via their index
- Elements can be concattenated to the list
List :
Index :
List example
- When the program starts fruits will be added to the fruit list.
- After
the fruits are added the Sprite will, as long as there are fruits in
the list, say the name of the last fruit in the list and then remove it
from the list.
- Queues and Stacks are two versions of lists with different properties
- In
a queue the first element that is added to the queue (enqueue) is the
first to be taken from it (dequeue) Called First in, First Out (FIFO)
• E.g. The checkout line in a supermarket is a queue - In
a stack the last element to be put(pushed) on the stack is the first to
be taken off the top(popped) Called Last in, First Out (LIFO)
• E.g. A pile of books can be described as a stack
- Rules:
● Rock beats Scissors
● Scissors beats Paper
● Paper beats Rock - Exercise: Code a Rock, Paper or Scissors game in Scratch:
● You make a choice of Rock, Paper or Scissors with the keys “r”, “p” or
“s”
● The computer makes a random choice Rock, Paper or Scissors
● The result is displayed - (Bonus if you use a list, e.g. The values of “rock”, “paper” or
“scissors” are all player choices)
Subroutine
A subroutine (procedure, function, routine, method, or subprogram)
- Portion of code within a larger program that performs a specific task and is somewhat independent piece of code.
– Used to structure the code
– Used when repeated calls need to be made
– Reduces the cost of developing and maintaining a large program
and increases its quality and reliability. - Subroutines, collected into libraries, are an important mechanism for sharing software.
AppInventor Rock, Paper and Scissors
- Create 3 buttons
● Rock
● Paper
● Scissors - Display the result of your choice against a random AI
- Think from Scratch
Klik gambar untuk memperbesar/memperjelas
Between a rock, a paper or scissors
- A drama about communication in one act
- Sceen: A Rock, Paper, Scissors tournament
- Actors
- Clients – Participates in the tournament
– Name: Rick, likes to roll with Rock
– Name: Piper, likes to fold with Paper
– Name: Saussage, likes to run with Scissors
● Server – Handles the Rock, Paper, Scissors tournament requests, respones and data storage
– Gets players name and responds with player results
– Responds with all stored player names if requested
– Stores player name and move
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| Klik gambar untuk memperbesar/memperjelas |
Communication Protocols
- How
do you make the devices (e.g. PC or Smartphone) communicate with each
other in order to register Rock, Paper or Scissors players, moves and
results?
● Excersice: Write down in pseudocode how you would handle the communication
- The devices do not know that other devices exist. Therefore the webpage
serves the clients(apps) and stores information. - A webpage has been set up http://icsp2011rps.appspot.com/
1. If there is no name registred notify that a name is missing
2.Else show the options “Store Move” and “Compete against an opponent”
2.Store a move on the server in the registered name
1.Play a move
2.Store the move on the server's data base
3.Compete against an opponent. The moves and opponents are stored on the server
1.Chose an opponent listed in the server's database
2.Play a move
3.Calculate the result
4.Show the result
Register a name
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Chose to Store Move or Play Opponent
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Choose a Move
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The lowest protocol deals with physical interaction of the hardware. Every layer above
adds more features.
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