1320 Principles Of Computer Science I

Transcription

1 1320 Principles Of Computer Science I Dr. Thomas Hicks Computer Science Department Trinity University 1 1

2 2 Read Course Outline! Linked To My Schedule Page

3 3

4 4 Check Schedule Page Daily! /1320/schedule.html We will often, but not always, discuss upcoming assignments check the page! Hints-Reading Assignments-Written Assignments/Labs!

5 5

6 6 Printing! Use Computer Science Printers Only For Your Computer Science Homework!!!! Print Only What Is Necessary!

7 7 Computer Science & Computer Programming

8 8 Computer Science Computer Science is the study of the Theoretical Foundations of of Information and Computation & of Practical Techniques for their implementation and application in computer systems.

9 9 Computer Programming Computer Programming is the process of Designing, Writing, Testing, Debugging / troubleshooting, & Maintaining. the source code of computer programs.

10 10 Who Is The Computer Scientist?

11 11 Time Distribution [From S.E. Text] What Do Computer Scientists Do With Their Time? 20% Non-productive activities 30% Workingalone 50% Interaction with other people Once A Computer Scientist Learns How To Write Code, The Computer Scientist Does Much More Than Just Sit & Work In Front Of His/Her Computer(s)!

12 12 How Does The TU Computer Scientist Learn To Write Code?

13 13 TU 4 Courses To Prepare You To Program! 4 Really Serious Programming Courses In The Major CSCI 1320 Principles Of Computer Science I CSCI 1321 Principles Of Computer Science II CSCI 2320 Principles Of Data Abstraction CSCI 2322 Principles Of Functional Programming Maybe Algorithms? CSCI 1320 Most Of You Should Plan On Devoting An Average About 9-10 Hours Per Week Designing, Writing, Testing, & Debugging Programs!

14 14CHARGE CSCI 1320 Principles Of Computer Science I Required For Their Major

15 15 Who Takes CSCI 1320 Principles Of Computer Science I? Understanding Natural Science and Technology or Support Major

16 16 Why Would You Care If You Like Computer Science?

17 17 Average Salary - Software Engineer

18 18 Average Salary - Database Administrator

19 19 Average Salary - Project Managers

20 20 Computer Science: A Young Science

21 21 Computer Science Is Often Considered A Young Science Founding Fathers [1] Babbage Difference Engine

22 22 Alan Turing & Alonzo Church

23 23 Giant Brain US Army Balistic Research Center in Maryland [2]

24 24 Software

25 25 What is Software

26 26 BIOS Software

27 27 Operating System (OS) Software Operating System determines how the user will interact with the computer.

28 28 Software Hardware

29 29 Hardware Computer Scientists Have To Know More Than Just How To Write Code

30 30 Mother Board ASUS Rampage II Extreme For I7 Intel Processor

31 31 Install The I7 Processor

32 32 Processor With Cooling Fan DX58SO Socket 1366 For I7 Intel Processor

33 33 Machine Language Programming

34 34 Processor Cycles Each Cycle the computer Loads an Instruction and Executes It. There was a time when Programming was done by Writing the Binary Instructions that the machine executes. We refer to the language of these binary instructions as Machine Language.

35 35 The Stupid Computer Only Understands 0 & 1 Every Processor, or processor family, has its Own Machine Code Instruction Set. Instructions are Patterns of Bits that by physical design correspond to different commands to the machine. Bits are 0 & 1

36 36 The First Generation Of Programming Was Done With Machine Language Programming If eight digit binary codes are used, there are 2 8 (256) numbered instructions from to Machine language instructions for adding two numbers could be something like the following: Writing a Program That Says Hello World Could Require Thousands Of Lines Of Code.

37 37 Processor Instruction Sets The Processor Instruction Set is thus Specific to a class of processors using (much) the same architecture. Successor, or Derivative Processor Designs, often include all the instructions of a predecessor and may add additional instructions

38 38 Multiple Processors/Cores CPU's of today often have more than one core/processor on board. Parallel Computing is a type of computation in which many calculations are carried out simultaneously, or the execution of processes are carried out simultaneously. Parallel Processing Large problems can often be divided into smaller ones, which are then solved at the same time. These smaller tasks are then assigned/threaded to other processors and run concurrently.

39 39 Computer Voltage Modern Computers work by Regulating the Flow of Electricity through Wires. In Today s Electronics, the electric flow has been reduced to tiny elements that have been etched into silicon (tens of nanometers across) Voltage, on the wires, is used to indicate the State of a bit. Voltage is either ON (1) or OFF (0)

40 40 Transistors The wires connect up Transistors that are laid out in a way that allow logical processing. Modern Computer Processor will include literally hundreds of millions of transistors.

41 41 von Neumann Architecture Most Modern Computers are built on a variation of the von Neumann Architecture Memory stores both Data & Programs Bus is the interstate for instructions and data

42 42 Assemblers & Assembly Language Programming

43 43 The Second Generation Of Programming Was Done With Assembly Language Programming Assembly Instructions are also Processor Dependent LDA 15 LDB 20 ADD,B,A Individual Instructions that computers can do are typically very simple. Computers get their speed instructions can be done very quickly. Assembly Language is more readable than Machine Language An Assembler, is a program which Translates the Assembly Instructions into Binary Code

44 44 About Assembly Instructions When using the early Assembly Languages, One Line of Assembly Code (1 Instruction) was translated into One Line of Machine Code. Macros were added to Assembly Language One Line Assembly code might generate hundreds of lines of Machine Code. Operating Systems, Micro Controllers, Computer Games, Video Cards, etc.

45 45 Billions Of Instructions Per Second Computers Instruction Cycle a few gigahertz. Computers Run a few billion instructions every second.

46 46 About Learning

47 47 About Learning Active Study lzzoahxl3ymkhye6a3gqfghdmay&url=http%3a%2f%2fwww.dartmouth.edu%2f~acskill s%2fdocs%2fstudy_actively.doc&usg=afqjcngsxkipwcmr03ik3ehmdhmjaulflq&sig2= VomF-zP7yLpCkP1Dn2f9HA&cad=rja You Remember 10% of "What You Read" You Remember 20% of "What You Hear" You Remember 30% of "What You See" You Remember 90% of "What You Do" Other Similar Studies You Remember 30% of "What You Read & Hear" You Remember 50% of "Read, Study, Highlight, Go Over & Over"

48 48 You Read You Remember 10% of "What You Read" I hope you read/study the reading assignments in the text! I hope you read/study the slides I Will give you Homework In Which Some Of The Questions You Answer Will Come From The Textbook.

49 49 You Hear You Remember 20% of "What You Hear" Come To Every Class - Take Notes Some Of The Information On Exams/Quizzes Will Be Available Only In Lecture! I Will give you Homework In Which Some Of The Questions You Answer Will Come From The Lecture.

50 50 You See You Remember 30% of "What You See" Come To Every Class - Take Notes - You Will See Me Write Lots Of Code - Did I Say Take Notes! Hand Writing The Answers On The Homework (where required) Really Seems To Help Students Remember Both The Coding Techniques & The Non-Programming Topics. Unless You Have Some Physical Deficit That Prevents You From Writing, You Will Be Asked To Hand-Write The Answers To The Non-Programming Portions Of Labs.

51 51 You Do (1/2) You Remember 90% of "What You Do" Come To Every Class - I Will Give You The Opportunity To Type Some Code - Along With Me - PRACTICE! You Will Not Always Keep Up - OK Take Notes Or Look On With A Neighbor When You Get Behind/Lost The Slides Will Contain A Lot Of Code I Recommend That You Actually Type Most Of This Code Before You Do The Programming Components Of The Labs. (Be Sure To Do This Before The Next Class) A Lot Of These Skills Seem To Best Get Cemented Into The Brain By Way Of Fingers Working The Keyboard!

52 52 You Do (2/2) You Remember 90% of "What You Do" I Will give you Homework In Which Some Of The Questions You Answer Will Come From The Textbook. At Least 80% Of Your Exams/Quizzes Will Be Taken From The Questions (Or Similar Questions) & Coding (or Similar Coding & Functions)

53 53 I Have Tried To Design The Course For Success I have had one 1320 Class in which everyone bought into these recommendations. They came to almost all classes They took notes They usually started their homework the day it was assigned They came in with questions any time they were confused They did not get behind - Almost all labs were turned in on time They All Earned An "A" in I have had classes with less than 20% A's

54 54 Compilers & High-Level Languages

55 55 About Compiler Instructions println ( Hello World ) The Scala instruction above is translated into thousands of lines of Machine Code. The Scala instruction above is the same for all processors & all operating systems MUCH FASTER PROGRAMMING!

56 56 The Scala Language Scala is a very High Level language that allows you to communicate ideas to the computer in a rather concise way and gives you access to a large number of existing libraries to help you write programs that are fun or interesting.

57 57 Compile Once Execute Binary Many Times 1 Byte = 8 Binary Bits 449,024 x 8 = 3,592,192 Bits To Say Hello World!

58 58 Interpreters & Programming Languages

59 59 Scala Interpreters Scala can be run in an Interpretive Environment. An Interpreter takes one instruction line translates it into binary executes that binary and continues to the next instruction in the program. Get next order would be converted to binary each time it is executed (inefficient, but works) Interpreted code generally slower than compiled code Interpreted Programs easier to debug

60 60 Scala Portability Scala can be compiled as well. Scala code is Very Portable Scala runs on Java Virtual machine (JVM) this ensures the portability to all the underlying platforms

61 61 Scala Is Multi-Platform

62 62 Creator of Scala Scala Created By Martin Odersky

63 63 Multi-Platform Scala Was Released in 2004 Official Website is Scala Is Multi-Platform 1. Windows 2. Linux/Unix 3. Mac 4. Java Virtual Machine 5..NET initiative underway!

64 64 Scala Is Open Source

65 65 Open Source Free Scala Is Open Source Many Contributors

66 66 Commercial Backing

67 67 I Encourge You To Install A Copy Of Scala On Your Computer

68 68 Full Blown Programming Languages

69 69 Scala Is A Powerful Language There are many full-blown, multi-purpose Programming Languages C, C++, & Java are among the best known Powerful! Scala is a new full-blown programming language.

70 70 There Are 3 Major Computer Programming Paradigms

71 71 Imperative Programming Scala There are many and a number of approaches (paradigms) to programming. Imperative Programming 1. The programmer specifically states how to do things 2. The values stored by the computer are readily altered during the computation.

72 72 Functional Programming Scala Functional Programming was born out of the mathematical notions of lambda calculus (Church) Functional Programming 1. No mutable state you have functions that take values and return values, but don't change anything else along the way

73 73 Object Oriented Programming (OOP) Scala Object Oriented Programming is the new paradigm Object Oriented Programming 1. The Data, and the Functions that operate on the data, should be bundled together into things called Objects called ENCAPSULATION Scala is purely Object Oriented

74 74 Scala Is A New Hybrid Language Scala can be programmed exclusively using the Imperative Paradigm! Scala can be programmed exclusively using the Functional Paradigm! Scala is purely Object Oriented & can make heavy usage of the OOP Paradigm.

75 75 How To Start Scala In Windows In CS Labs

76 76 Start REPL Interpreter Read-Evaluate-Print Loop

77 77 How To Exit From Scala In Windows

78 78 Exit REPL Interpreter :q

79 79 How To Start Scala In Linux

80 80 Start REPL Interpreter Read-Evaluate-Print Loop

81 81 How To Exit From Scala In Linux

82 82 Exit REPL Interpreter :q

83 83 Using Scala As A Calculator

84 84 Basic Integer Operations Addition (+), Subtraction(-), Multiplication(*), Division(/) scala> Integers = 0, +/- 1, +/- 2,

85 85 Integer Division Integer Division(/) Discards The Remainder Comment Symbol (//)

86 86 Scala Has No Exponentiation Operator We can use the Power (pow) function from the math library.

87 87 Real Number Division The Decimal Point makes a number a real number. If any value is in an expression is real, the result is real. Double 8 byte real number.

88 88 Order Of Operations Correct! Innermost Parentheses First Exponentiation (Right To Left) Multiplication & Division (Left To Right) Addition & Subtraction (Left To Right)

89 89 MOD Modulus (%) returns the Remainder

90 90 REPL Read-Evaluate-Print Loop Under The Hood

91 91 REPL Scala supports Multiple Modes of Interaction. Scala can be run in an Interpretive Environment. REPL Read-Evaluate-Print Loop All Scala Data Members are Objects Scala Statement end with semicolan (;) semicolon inference inserts (;) for you

92 92 REPL Expression Evaluation res0 short for result0 5 Numeric Literal The results of the expression, entered into Scala, are (1) it gave it a name (res0), evaluated it (2+3=5) and gave it back(res0: Int = 5) Int is the type name that Scala uses for basic numeric integers.

93 93 REPL Expression Evaluation Colons(:) are used to separate things from their datatypes. Note that we can print the value stored in the named container (res0)

94 94 Creating String Variables & Constants

95 95 Naming String Objects String Variables var String Variables are symbolic names for containers that hold character data. Strings are delimited with double quotes. var first:string = tom creates a string variable, called first, and fills the container with tom When You Use var, you must initialize the variable with a value! You Can Force The Scala Interpreter To Select A DataType!

96 96 About String Variables var All Variables can be changed (String too!) When You Use var, you must initialize the variable with a value! You Can Force The Scala Interpreter To Select A DataType!

97 97 String Constants val val course:string = CSCI-2320 creates a string constant, called course, and fills the container with CSCI-2320 Constants (Course) may not be changed during program execution.

98 98 Naming Variables

99 99 Naming Objects Select Meaningful Variable/Constant Names Object Names Are Case Sensitive Conventions: payrate (camel naming convention) pay_rate PayRate

100 100 String Concatenation

101 101 Concatenation String Concatenate (+) is the process of combining strings

102 102 println

103 103 Concatenation & println print print the arguments passed println print the arguments passed and skip a line

104 104 Creating Integer Variables & Constants

105 105 Naming Integer Objects Int Variables var Int Variables are symbolic names for containers that hold Integer type data. -2,147,483,648 <= Int <= 2,147,483,647 (~+/- 2 billion) var age:int = 21 creates an integer variable, called age, and fills the container with 21 When You Use var, you must initialize the variable with a value! You Can Force The Scala Interpreter To Select A DataType! (generally)

106 106 About Int Variables var All Variables can be changed (Int too!) age = age + 1 Incrementing age -2,147,483,648 <= Int <= 2,147,483,647 Later We Shall Examine How Positive & Negative Integers Are Stored Later We When Shall You Discuss Use Why var, you noitems must Becomes initialize Negative the variable with a value! You Can Force The Scala Interpreter To Select A DataType!

107 107 Int Constants val val N:Int = 5000 creates an Int constant, called N, and fills the container with 5000 Constants (N) may not be changed during program execution.

108 108 Creating Double Variables & Constants

109 109 Naming Real Objects Double Variables var Double Variables are symbolic names for containers that hold real type data. val payrate:double = creates an double variable, called payrate, and fills the container with Computer Representation Of Real Numbers (Doubles) Is Not Exact! Scientific Notation

110 110 About Int Variables var All Variables can be changed (Int too!) age = age + 1 Incrementing age -2,147,483,648 <= Int <= 2,147,483,647 Later We Shall Examine How Positive & Negative Integers Are Stored Later We When Shall You Discuss Use Why var, you noitems must Becomes initialize Negative the variable with a value! You Can Force The Scala Interpreter To Select A DataType!

111 111 Principles Of Computer Science I CSCI 1320 Dr. Thomas E. Hicks Computer Science Department Trinity University Textbook: An Introduction to Programming with Scala By Dr. Mark Lewis