Fundamentals of Computer Science

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Fundamentals of Computer Science

• Ethan Cerami
• New York University
• Spring 2000

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Today

• Course Description
• Or, what am I getting myself into?
• Exams, Grades, Course Web Page, etc.
• The Lego Theory and the Course Syllabus
• Whats a Programming Language?
• Why Learn C?
• Hello, World! Program
• Your first taste of real programming.

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How do I get these slides?

• Occasionally, I will use present PowerPoint
  slides.
• Whenever I do so, I will post them to the course
  web page
• Go to http//cs.nyu.edu
• Click on Course Home Pages
• Click on V22.0380.002 Course Home Page

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Why is this class so _at_! Early?

• Yes, class starts at 800 am.
• Last semester, class started at 830 am. This
  semester, NYU gets cruel )
• Please try and stay awake!
• We will usually have a break at around 845. So,
  go get coffee.

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Course Description

• Official Description This is a course in
  computer programming concepts for students with
  little or no programming experience. The intent
  is to teach students to write both clear and
  efficient C programs by emphasizing structured
  programming principles. This course is intended
  as a first course for information systems majors,
  for students of other scientific disciplines, and
  for a functional introduction to programming.

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What the class is really about

• There are four main goals of this course
• 1. Basics of C
• 2. Core Concepts of Programming Languages
• 3. Basics of Software Development
• 4. Extra Topics

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1. Learn the Basics of C Programming

• C is a popular programming language, widely
  used in Industry.
• We will learn all the specifics of how to
  program in C.
• This includes all the peculiar rules that are
  specific to C.
• We will cover all the fundamentals Variables,
  For Loops, While Loops, Arrays, Pointers,
  Structures, etc.

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For Example

• / Sample C Program /
• include ltstdio.hgt
• define MAX_NUM 10
• main ()
• int i
• for (i0 iltMAX_NUM i)
• printf ("Number d\n", i)
• return 0

This program counts from 1 to 10. In a few
weeks, it will all make sense.
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2. Learn the Core Concepts of all Programming
Languages

• There are lots of programming languages
  available Pascal, Java, Ada, Lisp, Perl.
• All of these languages share core concepts.
• By focussing on these concepts, you are better
  able to learn any programming language.
• Hence, by learning C, you are poised to learn
  other languages, such as C or Java.
• By learning the core concepts, you are also much
  more marketable as you are able to learn new
  technologies much faster.

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For Example For Loops

• C has a construct called a for loop that
  enables a program to repeat actions over and
  over.
• Every other language also has a for loop.
• Hence, by learning about for loops in C, you
  can easily learn for loops in C or Java.

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3. Learn the Principles of Software Development

• Building high quality software is very difficult.
• The course therefore presents the syntax and
  concepts of programming, but also presents
  strategies for building real software that
  addresses real problems.
• I will also try to bring real-world industry
  experience to class.

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For Example Principle 61 Transition from
specification to code is not easy.
Specification for building an Airline Reservation
System
Actual Software that gets the job done.
Alan M. Davis, 201 Principles of Software
Development, (McGraw Hill, Inc, 1995.)
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4. Extra Topics

• Try to imagine all the new kinds of computers
  that will arrive in the next generation or two.
  Imagine what we -- actually our children and
  grandchildren -- will do with them all. One
  thing is sure whatever wild visions you can
  conjure are too tame.
• -- Peter J. Denning, Beyond Calculation The
  Next Fifty Years of Computing (ACM 1997.)

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Extra Topics in the Past

• DigiScents computers capable of producing
  smells (!)
• TCP/IP understanding how the Internet routes
  packets to the correct destination.
• Virtual Reality and 3D Chat
• Computer Animation
• The technology behind Burger Kings Whopper.

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On to Administrative Issues...

• Books
• Software
• Grades
• Getting Help
• Course Home Page

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Required Text Book

• Deitel and Deitel,
• C How to Program
• Very comprehensive text book.
• Available at the NYU Book Store.

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Supplemental Book

• Kernighan and Ritche, The C Programming Language
• -- Written by the creators of C.
• -- A good reference, but not an easy read.

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Annotated Programs Packet

• Word Document that contains all the programs to
  be discussed in class.
• Available on the Course Web Site.
• Some are taken from the book, some were created
  in previous semesters.
• You can also download all the programs directly
  from the web site, and try them out within your
  own compiler.
• Please bring the packet to every class!

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Software

• We will use the Borland C compiler.
• Borland C is available in some Stern Labs and
  all the ACF Labs.
• You can also purchase an academic version for
  50 from the NYU Computer Bookstore.
• If you buy a copy, you want to buy Borland C
  Builder 4.0, and install the CD named, Borland
  C, Version 5.0 (you wont need the other CDs
  for this class.)

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Other things you will need

• Email Account All homework assignments must be
  submitted via E-Mail.
• Floppy Disks If you are planning on using the
  NYU Computer Labs, make sure to save your
  programs to a floppy disk.

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Grading

• All homework must be done individually. The
  Grader will be checking for cheating.
• Also, see the late policy on our web site.
• How your grade is determined
• homework 40
• midterm exam 25
• final exam 35

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Getting Help

• Many students find this course very challenging.
  When you get stuck, ask for help!
• 1. Office Hours Every Thursday, 930 am -
  1130 am, 419 Warren Weaver Hall.
• 2. E-Tutor E-Tutor is required to write back
  in 24 hours. (See Web Page for
• E-Tutors Email Address.)
• 3. Yahoo! Club Write your questions here, and
  other students might be able to help out.

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Course Home Page

• Everything regarding the course is available via
  the Course Home Page. So, check it early and
  often.
• How to get to the Home Page
• Go to http//cs.nyu.edu
• Click on Course Home Pages
• Click on V22.0380.002 Course Home Page

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The Lego Theory

• The Lego Theory Complex software is built with
  simple,
• basic building blocks.

Check out http//www.lego.com/justbuild/buildpag
e.asp
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Lego Theory (cont.)

• Lego theory goes by many different names
  abstraction, divide and conquer, object
  orientation, etc.
• Nonetheless, it represents the most powerful idea
  in computer science, and the most important thing
  you will learn this semester.
• If nothing else, I hope you remember the Lego
  theory five years from now.

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Lego Theory Applied Basic Example
Suppose you want to print your name five times.
Main Lego Block For Coordinating everything
Lego Block Printf() for displaying your name
Lego Block For loop for repeating actions
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Lego Theory Applied Searching the Web

• Suppose you want to build a piece of software
  that searches the web.

Lego Block 1 Retrieves user search keyword and
sends the query to Lego Block 2. Once it has
results from Lego Block 2, send it to Lego Block 3
Lego Block 3 Formats the results in a nice
graphical interface.
Lego Block 2 Huge storage of web sites.
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Searching the Web (cont.)

• By using the Lego Theory, you break complicated
  tasks into smaller, simpler subtasks.
• You can also more easily divide up the work, and
  more easily figure out where things go wrong.

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How we will use the Lego Theory

• Each week, we will introduce a new basic building
  block. For example, this week we will cover
  input and output. Later on, we will cover
  variables.
• By combining these blocks, we can start creating
  more and more powerful programs.
• By the end of the semester, you will have all the
  basic blocks for building very sophisticated
  software.

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Syllabus First Half of Semester

• Week 1 Basic Input/Output
• Week 2 Variables, Basic Mathematics
• Week 3 If/Else, While Loops
• Week 4 For Loops, Logical Operators
• Week 5-7 Functions

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Whats a Programming Language?

• Programming Language A language used to create
  computer applications.
• Examples of Programming Languages
• C
• C
• Pascal
• Java (Internet)
• Cobol (COmmon Buisiness Oriented Language)
• Ada (mainly used by Department of Defense)

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Why Learn C?

• So, why pick C?
• 1. Its a very powerful, very fast language.
• 2. C is one of the most widely used languages.
  People use it in the real world
• 3. It forms the basis of more advanced
  languages, such as C and Java.

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C v. Pascal

• Lots of other introductory classes focus on
  Pascal.
• Pascal is easier to program, but its only used
  in Academic settings. And, this course tries to
  focus on practical business applications.
• "Pascal keeps your hand tied. C gives you enough
  rope to hang yourself."

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History of C

• Developed in 1972 at Bell Labs (now part of
  Lucent Technologies)
• C does not stand for anything C evolved from a
  language called B (which also didnt stand for
  anything.)

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ANSI C

• ANSI C American National Standards Institute
• Standard C that runs on most operating systems.
• There are lots of operating systems currently is
  use Windows, Macintosh, UNIX, IBM Mainframes.
  You can run ANSI C on any of these platforms.
• Portable a program that runs on more than one
  operating system.

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Your first C Program
/ First Program in C / include
ltstdio.hgt main() printf("Hello, World!")
/ Wait for user to Press Enter /
getchar()
Hello, World!
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Comments

• / First Program in C /
• Text that helps you and others to understand
  the program
• Completely ignored by the computer
• Anything between / and /
• A Program with no comments is a very bad
  program.

Tip You must include comments in your homeworks.
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include ltstdio.hgt

• include tells the compiler to include certain
  library files.
• stdio.h stands for Standard Input/Output header
  file
• stdio.h is required any time you use printf or
  scanf.
• Other libraries math.h, graphics.h

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main () function

• Every C program must have a main function.
• Every program begins execution at the main
  function.
• No matter how big your program, you must always
  have a main().
• We will return to a formal definition of
  functions later.

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Blocks of Code

• Any code between and is considered a block
  of code.
• In this case, anything between and is
  considered part of the main function.
• Hence, when we run main, we will run everything
  within the block.

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printf("Hello, World!")

• Displays a string of text.
• String any text appearing within quotes.
• Printf is an example of a statement.
• Note that all statements in C end with a
  semi-colon.

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/ Wait for user to Press Enter / getchar()

• getchar() pauses the program until the user
  presses the ENTER key.
• As we will soon see, this pause is important when
  running programs under Borland C.
• Without the getchar(), the program will run and
  exit so fast that you will not see any output.

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Quick Recap
Comments
/ First Program in C / include
ltstdio.hgt main() printf("Hello, World!")
/ Wait for user to Press Enter /
getchar()
include library
main () function
printf()
Block of Code