CSC 160CSC 160Computer ProgrammingComputer Programming

for Non-Majorsfor Non-Majors

Lecture #1: What is Programming?Lecture #1: What is Programming?

Prof. Adam M. WittensteinProf. Adam M. Wittenstein

Wittenstein@adelphi.eduWittenstein@adelphi.edu

http://www.adelphi.edu/~wittensa/csc160/http://www.adelphi.edu/~wittensa/csc160/

What's this course about?

● Fundamentals of computer programming● Going from a word problem to a working

program● Designing programs to be modified and reused● How computer scientists think

What's this course not about?

● A particular programming language– (e.g. Scheme, Java, C++, perl, ...)

● A particular programming environment– (e.g. DrScheme, Visual Studio, ...)

● Designing and writing Web pages● Arithmetic

However, we have to use...

● A programming language– (we'll use Scheme)

● A programming environment– (we'll use DrScheme)

● The Web– (for textbook, assignments, announcements, ...)

● Arithmetic (as an example we all know)

Who should take this course?

● Non-CS majors for Math/CS distribution credit● Math and CIS majors for programming credit● Undecided majors to “test the waters” of

programming● CS majors as a “warm-up” to CSC 171

Who should not take this course?

● CS majors for major credit● End-users and Web page authors● Students needing to fulfill the Second

Competency requirement ● Students looking for a “cake” course

– This course does require an average of 9 hours a week: 3 in class, and 6 in reading and homework

This course as a Liberal Arts Requirement

● This course trains you to think logically by focusing on Design Recipes: beginning from a problem statement and ending with a well-organized solution, a skill that is useful throughout college and life, regardless of your choice of profession.

● Many professions require some form of computer programming. Some examples include: accounting, photography, music, and of course, computer science.

I. A First Look at How to Design I. A First Look at How to Design ProgramsPrograms

Computers vs. People

● Computers do many of the same things people do, such as: --calculating numbers --remembering information

● Some differences are that computers are: --faster and more accurate --they do not get bored

Defining Programming

● This course is about Computer Programming.

● To program a computer, one needs to:

--Figure out how they would solve a problem. --Present that explanation to the computer.

More on Defining Programming

● Unfortunately, computers are literal-minded and have no intuition. So your explanation has to be more precise than if you were explaining something to a human being.

● Therefore, to program a computer one needs to:

--Figure out precisely how they would solve a problem.

--Present that explanation to the computer.

Design Recipe (in Life)Design Recipe (in Life)

To solve To solve anyany problem, in problem, in anyany area (not just area (not justprogramming), requires three steps: programming), requires three steps:

Figure out what you need to do. Figure out what you need to do.

Do it.Do it.

Check that you did it right. Check that you did it right.

Design Recipe (in Programming)Design Recipe (in Programming)

To make this recipe useful, we need to adapt itTo make this recipe useful, we need to adapt itmore specifically to computer programming:more specifically to computer programming:

Figure out Figure out preciseprecisely what you need to do. ly what you need to do.

Tell the computer how to do it.Tell the computer how to do it.

Check that the computer does it right. Check that the computer does it right.

II. Types of KnowledgeII. Types of Knowledge

Imagine this assignment...

● 20-page paper● Due at end of semester● On Napoleon's invasion of Russia

What kinds of knowledge are needed?

1. How to write a 20-page paper2. How to finish a long-term project on time3. Napoleon & Russia

Imagine this assignment...

● 20-page paper● Due at end of semester● On Napoleon's invasion of Russia● In Swedish● With a quill pen

What kinds of knowledge are needed?

1. How to write a 20-page paper2. How to finish a long-term project on time3. Napoleon & Russia4. Swedish language (spelling, vocabulary,

grammar, idioms…)5. How to use a quill pen

In a programming course...

1. How to structure a program(understand the problem and design a solution)

2. How to plan your time(going through the steps of the Design Recipes)

3. Content-area knowledge(math, graphics, economics, physics, spelling, etc.)

4. Scheme (or C++ or Java or whatever) language5. How to use the software & hardware

Our Focus

Although we need to do all five of these things, our goal is learning how to do the first two.

However, all problems require:● Knowledge (in some content area)● Language (like English)● Thinking Tools (like your brain)

Content-area Knowledge

● This is not a course on math or science or English, but we will solve problems from these disciplines.

● No need to worry, I will either give you the required information, or you will be allowed to look it up.

The Beginning of Computers

● Originally computers were about numbers. --Scientists used them to solve equations. --Businesses used them to prepare the payroll.

● We were rescued from this boring state of affairs mainly by researchers in artificial intelligence. --They wanted computers to be more like people --They wanted the computer to treat ideas in

general rather than just numbers. ● From this, the LISP programming language was

invented. A similar (but simpler) language is Scheme.

Writing and Thinking

● Outside this class, we write in a language called English. Inside this class, we will write in a language called Scheme.

● Outside this class, we use our brain to think about what is being said in English. Inside this class, we use Dr. Scheme to think about what is being said in Scheme.

Scheme is to English

● Scheme - The programming language that we will use.

● Dr. Scheme - the program that we will use to run programs written in Scheme.

As Dr. Scheme is to the brain

Choosing a Language to Speak

● We can speak in any language. Why do we choose English?

Choosing a Language to Speak

● We can speak in any language. Why do we choose English?

● Because we already know enough of it to understand the basics of how it works.

Choosing a Language to Program In

● We can program in any programming language. Why do we choose Scheme?

Choosing a Language to Program In

● We can program in any programming language. Why do we choose Scheme?

● Because we can quickly learn enough of it to understand the basics of how it works.

● Because we do not want to spend half our time on obscure language rules, which would be necessary for a Java or C++-based course.

III. Communicating with the ComputerIII. Communicating with the Computer

A few preliminary definitions

● Program - A set of instructions that tell the computer how to perform a task

● Programming - Writing a program ● Programming language - a language of

instruction for a computer program ● Data - Information that is used by a program ● Operations - The individual instructions

performed by the computer ● Primitive operations - The basic operations

performed on data of a specific data type. – e.g., +, -, *, / are primitive operations performed on

integers.

Some typical problems in English

● The temperature is 350C; convert this temperature into Fahrenheit.

● Are there 7 days in a week?

● How do we cover someone’s face in a picture?

What the computer would think?

● The computer would have no idea what we are asking it.

What the computer would think?

● The computer would have no idea what we are asking it.

● We must communicate with the computer in a language that it understands.

What the computer would think?

● The computer would have no idea what we are asking it.

● We must communicate with the computer in a language that it understands.

● We will communicate in the Scheme language.

Types of Data

There are many types of data. They are split into two general categories:

1) atomic (simple) data – numbers, booleans, symbols, images, etc.

2) compound data – structures and lists composed of other pieces of data. For example, a series (list) of numbers.

The next several chapters deal only with atomic data.Sometime after the midterm, we will extend ourprogramming to compound data.

IV. Preparing for Next ClassIV. Preparing for Next Class

In summary…

● Today we were introduced to:--the ideas behind programming--using a Design Recipe--types of knowledge--how computers think

Reading assignments due Thursday…

● Before next class, please read: --Course Syllabus

--Simply Scheme: Forward, Preface, pages 1-7 --How to Design Programs: Preface, Chapter 1 --Joys (and Woes) of the Craft of Programming

which covers the topics in today’s lecture.

● Also, please read chapter 2 in Simply Scheme, which covers what we will discuss next class.

Homework #1 (due SUNDAY)

● [20 pts] Log sheet (hand it at Tuesday’s class)

● [20 pts] Posting on Blackboard (minimum 30 words)

● [60 pts] Essay on Readings (about 300-600 words)

About the reading assignments…

● It is of the utmost importance that all reading assignments are done on time, especially in a Computer Programming course.

● Since this is an undergraduate collegiate course, the lectures are designed to assume all prior readings have been completed and understood.

● If there is any part of a reading assignment that you do not fully understand, please e-mail me prior to class letting me know specifically what part, or ask at the beginning of the next class.

Course web page:http://www.adelphi.edu/~wittensa/csc160

I recommend you visit the web page frequently as Iwill post important information including:

– the lecture slides (so you can find out what you missed, if you are absent)

– reading and programming assignments

– assignment corrections (and perhaps, extensions)

– class cancellations (in the event of weather, or some other emergency)

Next time…What are functions?

● In high school math, you were asked to find f(5) when f(x) = x + 3.

● To do this, you replaced the x with a 5, so f(5) = 5 + 3 = 8.

● We will learn about functions in a more general sense.

● In fact, we will see that functions are not just for numbers.