Jeroo – Chapter 4 –

1. Jeroo – Chapter 4 – Simple Programs

2. Basic Concepts Jeroo (Java/C++/object-oriented) programing style is case-sensative. Be consistent in coding Logic must be well designed Must be easy for someone to read and understand the program’s source code Whitespace, comments, and descriptive identifiers all contribute to making a program easier to read.

3. Basic Concepts • Whitespace – consists of blank lines, spaces, tabs • Should be used to organize code into groups • Comments are phrases that a programmer inserts into a program to provide anyone who reads it additional information (Just like HTML) • Ignored when the program is run • Begins with // and continues until the end of the line

4. Form of a Jeroo ProgramMain Method The main method describes how to use one or more Jeroos to solve a specific problem. Everything that appears between the braces should be indented 2 or 3 spaces. Method main ( ) { ……. }

5. Declaring and Instantiating Jeroos • Every Jeroo program uses 1 to 4 Jeroo objects to solve a problem. • First declare the Jeroo, then Instantiate the Jeroo Jeroo name= new Jeroo(…); • For the declaration, the programmer must provide a name for the Jeroo object. • First character must be a letter, $, or underscore (_) instantiation declaration

6. Declaring and Instantiating Jeroos • Instantiation • A request that the Jeroo object be created • The crucial part is the constructor, which has the form of: • Jeroo (…) • The parentheses are filled with the initial values of the attributes for the Jeroo • Every Jeroo has 3 attributes: location, direction, number of flowers in its pouch.

7. Declaring and Instantiating Jeroos • If the initial values are not specified, then the constructor provides the default values: • Location – (0,0) • Direction – East • Flowers -- 0

8. Our code so far method main ( ) { Jerooname= new Jeroo(…); }

9. Instantiation Portion Now we will look at the code in red Method main () { Jeroojessica = new Jeroo(…) }

11. Now our code….. Method main () { Jeroojessica = new Jeroo(2,5,North,4) } What is the default location? How many flowers does Jessica have? What direction is Jessica facing?

12. 4.4 Action Statements • Is a request that a Jeroo perform a specific task. • The task can be either: • One of the basic action methods that are part of the Jeroo language • OR a Jeroo method that has been written by the program • We will concentrate on ones that are part of the Jeroo language.

13. Syntax of an action statement jessica.hop(3)

14. Syntax of Action Statement The Jeroo language inclues the 7 action methods shown on the next slide(s). Three (3) of these: give, turn, hop require an argument value. On the next slide, we will look at a table of actions

16. What happens in the following code? Method main ( ) { Jerooplace = new Jeroo (); place.hop(4); place.turn(RIGHT) place.hop(2); place.plant();

17. Answer these questions about the code? What are the final coordinates of Jeroo place? There is a logic error in the code. What is it? There are two syntactical errors in the code. What are they?