BFOIT - Introduction to Computer Programming
Background
jLogo Programming
- Commanding a Turtle
- Pseudocode
- Adding New Commands
- Iteration & Animation
- Hierarchical Structure
- Procedure Inputs
- Operators & Expressions
- Defining Operators
- Words & Sentences
- User Interface Events
- What If? (Predicates)
- Recursion
- Local Variables
- Global Variables
- Word/Sentence Iteration
- Mastermind Project
- Turtles As Actors
- Arrays
- File Input/Output
Java
- A Java Program
- What's a Class?
- Extending Existing Classes
- Types
- Turtle Graphics
- Control Flow
- User Interface Events
Appendices
Updates
- December 13, 2008
- January 6, 2012
- March 15, 2013
- January 20, 2014
- February 13, 2014
- July 29, 2014
- January 18, 2016
- January 29, 2016
Lastly
Pseudocode - Screencast Script
Welcome to BFOIT's Introduction to Computer Programming website. This is a short screencast overview of the third lesson: Pseudocode. In the first lesson you learned about the gap between us humans and our native languages and a computer and it's native language. In these lessons we are learning to program with Logo, a high- level programming language; it is about as close as we can get to the English language. But the version of Logo we are using only knows approximately one hundred and fifty words - much less than you or I know. And, it has some strange punctuation rules. In this lesson you will see how to use English to get you a step closer to the Logo code you write. -------------------------------------------------------------------- [ position to Summary ] Pseudocode uses structural concepts of computer programming along with a native language. We are going to use pseudocode combined with an age-old method for solving math problems - George Polya's steps which he outlines in his book How to Solve It. His steps are: 1. Understanding the Problem, 2. Devising a Plan, 3. Carrying Out the Plan, and 4. Looking Back. -------------------------------------------------------------------- [ Bring up the Windows Paint program with an image of TG with a ] [ BowTie loaded into the background ] Let's work through an example. It has to be very simple to keep this screencast short. Let's get the turtle to draw a bowtie. To understand the problem, what our Logo program will consist of, I'll just sketch an example of a crude, artistic rendition of a bowtie. So, it looks like we need to get the turtle to draw two triangles, each a sort-of reflection of the other. I think we now understand what our program needs to do. We've completed the the first step of phase. -------------------------------------------------------------------- Next I'll devise a plan; I'll describe what I'm going to do in English, as Logo comments in TG's editor. [ show bringing up the editor and type in the first few comments ] [ ; BowTie ] [ ; initialize: clear the canvas. make sure the turtle is at home, ] [ ; heading north, with a wide, yellow pen ] [ ; draw the triangle to the right of home, ending back at home ] -------------------------------------------------------------------- - show typing in the last line of pseudocode [ ; hide the turtle ] -------------------------------------------------------------------- So now it's time for carrying out the plan. I'll convert the pseudocode to Logo instructions. [ type in the first line of instructions ] [ home clean setheading 0 setpencolor 6 setpensize 10 ] -------------------------------------------------------------------- One great thing about Logo programming environments is that they are highly interactive. Since I do not know the angles and lengths of the legs of the triangle I need, I'll just experiment [ right 45 forward 150 home right 15 forward 200 forward 50 ] [ right 90 right 30 forward 200 forward 20 home ] Now I can use the results of this experimentation to fill in the remaining Logo instructions. -------------------------------------------------------------------- [ With completed program in the Editor ] I've now completed the translation from pseudocode to Logo. Let's see how it looks. [ Choose the menu item: Window -> Editor -> Interpret ] Looks pretty good to me. -------------------------------------------------------------------- The Pseudocode lesson will walk you through writing a program that draws the "collection of boxes" exercise from the previous lesson. Go to it... and remember - HAVE FUN!