CS1321: Introduction to Programming

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CS1321Introduction to Programming

• Georgia Institute of Technology
• College of Computing
• Module 3
• Design Recipe Introduction

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Designing Programs
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Outline

• Prerequisites
• Basic Scheme Syntax
• Objectives
• Basic recipe for program design
• Purpose
• Examples
• Body
• Tests
• Reference
• HTDP Section 2.5 Designing Programs

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Road Map

• Foreign Language
• Grammar
• Vocabulary
• Phrases, Sentences
• Conversation

Computer Language Syntax Defined
Words Abstraction Problem Solving
Start conversing from the first day
Start solving problems from the first day
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Design Recipe

• Incredible way to guide your programming
  experience
• Well present examples of the Design Recipe in
  this lecture and many others
• For you HW, be sure to see the HW Skeleton linked
  on the course website under the HW section. It
  gives the format you are to use for homeworks.

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The basic design recipe Contract ltnamegt
ltvariable typegt -gt ltvariable typegt Purpose A
brief description of the problem Example
ltexample of what you would put ingt should
produce ltexample of what should
happengt Definition ltput your code
heregt Tests ltput your tests heregt
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Our revision... Name John Doe GT
Numbergt1234a Homework ltnumbergt (and more
see the HW Skeleton on the website under
Homework!) Collaboration Contract ltnamegt
ltvariable typegt -gt ltvariable typegt Purpose
A brief description of the problem Example
ltexample of what you would put ingt should
produce ltexample of what should
happengt Definition ltput your code
heregt Tests ltput your tests heregt
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Lets work through an example
Write a function area-circle that calculates
the area of a circle. It will consume a number
and return a number.
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Contract
Contract area-circle number -gt number
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Purpose
Purpose Calculate the area of a circle given
the radius
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Example
Example (area-circle 5) should produce
78.5
Alternatively
Example (area-circle 5) --gt 78.5
(area-circle 1) --gt 3.14
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Definition
Definition (define (area-circle radius)
( 3.14 ( radius radius))
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Tests
Tests (area-circle 5) expected 78.5 (area-c
ircle 10) expected 314
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Do I have to do this?
yes!
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Do I have to do this?
And it works!
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Summary

• You should now know
• Basic recipe for program designsee page 21 or
  http//www.htdp.org/2001-01-18/Book/node14.htm
• Purpose
• Examples
• Body
• Tests
• Recipes are required. See HW webpage and course
  webpage for more requirements regarding recipes
  and format for HW for this course.

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Assignments

• Read section I Processing Simple Forms of Data
• HW 1 is due tomorrow at noon..
• Keep reading newsgroup .announce every day.
• Lab 1 covering email and newsgroups is online,
  due tomorrow at noon.

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