1. Overview History Hardware Software Software Development Life Cycle
Programming Languages
Structured Programming
Defining the Problem
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2. History of computers First Generation computers (1951-1958)
vacuum tubes
used large amounts of electricity, heat,large and expensive
ENIAC - computed trajectories for U.S. Army
UNIVAC - first commercially available computer, census
Second Generation computers ( )
transistors, less heat
more reliable, less expensive
Third Generation computers ( )
integrated circuits
less heat, higher speed
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3. History of computers Fourth Generation computers (1971-present)
microprocessor => Personal Computer
Apple II (1977), IBM PC (1981)
ARPANET (1969)
WWW (1991)
Today - cheaper, smaller, better
Fifth Generation computers (present and beyond)
Artificial Intelligence
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4. Computer Components (Hardware)
Peripherals
Central Processing Unit ( CPU )
Input Device
Control Unit
Arithmetic Logic Unit
Output Device
Auxiliary
Storage
Device
Memory Unit ( RAM & Registers )
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5. Software Systems Software Programming Environment Application Software
Operating System – software that controls overall operation of computer
DOS, Windows, Unix, Linux
Programming Environment
Editor/Compiler/Interpreter/Linker/
Debugger
Application Software
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6. Software Development Life Cycle
Define the Problem (Analysis)
Design the Solution (Algorithm)
Code Solution (Program)
Test and Debug
Maintain & Document
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7. SDLC
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8. 1. Analysis What? Defining the Problem Requirements
Generate and document a clear problem statement
Need to talk to all stakeholders
Most common cause of software system failure traced to poor requirements gathering
IPO
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9. 2. Design
HOW?
Planning
Algorithm – expansion of steps in the IPO diagram
Flowchart
Pseudocode
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10. netPay = payRate * hrsWorked
Start
Input payRate
Input hrsWorked
netPay = payRate * hrsWorked
Output netPay
Stop
Pseudocode:
Input payRate
Input hrsWorked
netPay = payRate * hrsWorked
Output netPay
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11. Design tools pseudocode flowchart Can be done easily on word processor
Implements structured
design elements well
Not visual
No standard
Standardized
visual
Difficult to modify
requires special software to do on computer
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12. An Algorithm is . . .
Step-by-step procedures for solving a problem in a finite amount of time.
We are learning to write algorithms and the computer is simply a fast and flexible tool for implementing algorithms.
An algorithm is an ordered set of instructions such that:      (1) There are a finite number of steps.      (2) It takes a finite amount of time to execute the steps.      (3) Each step is precise in meaning, and “doable.”      (4) It solves a general class of problems.
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13. 3. Code the Solution Choose language Edit – create source program
Compile - translate
Syntax error – violate rules of programming language
Link
Create an executable program
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14. 4. Test and Debug Test with variety of data
Debugging: locating and correcting errors
Logic error or bug - flaw in algorithm
Run-time error e.g. Divide by zero
Programming packages usually have debugger software to help programmer
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15. 5. Maintain and Document
Maintenance – Changing and maintaining existing programs
Most coding is actually maintenance
Documentation – sometimes done by technical writers
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16. A Tempting Shortcut? DEBUG REVISE REVISE DEBUG DEBUG REVISE Shortcut?
CODE
GOAL
TEST
THINKING
CODE
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17. Programming Languages
Definition: languages with strict grammar rules, symbols, and words used to construct a computer program
Machine Languages
is not portable, runs only on specific type of computer
is made up of binary-coded instructions (strings of 0s and 1s)
is the language that can be directly used by the computer
Assembly Language
Mnemonic codes are used for the op. codes instead of binary, EXA: LDA N, SUB B
assembly language program must be translated into machine language before it can be executed, ‘assembler’.
High Level Languages
portable
similar to natural language
Requires compiler – translates high-level language into machine code
FORTRAN, Visual BASIC, COBOL, Pascal, Ada, C++, Java
most are standardized by ISO/ANSI
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19. Assembly Language
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20. C++ 1972 : C created by Dennis Ritchie at Bell Labs
=> 90% of UNIX is then written in C
1983: C++ - Bjarne Stroustrup at Bell Labs
1998 : ISO/ANSI standardization of C++
general-purpose programming language - many uses
Flexible - few restrictions
high demand for C,C++ programmers
high level/low level
Portable - leader in portability
programmer oriented-"written by a professional programmer for professional programmers"
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21. 1. Edit: write and type the program (source code) in C++ , Save as myProg.cpp
2: Compile: translate the source code into machine language => myprog.obj
syntax error – violation of the rules of the language. 
3: Link = bring in other code from libraries, bind the modules together, etc => myProg.exe
4: Run = run the executable file
 Logic errors (bug) – An error caused by a mistake in programming instructions.A logic error causes a program to operate wrongly or produce incorrect data, but not to stop working
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22. Structured Programming
Top-down Design– divide and conquer
Modularity
subprograms
Stepwise refinement
The Structure Theorem- Use 3 basic control structures to solve any problem
Sequence
Selection (if-then-else)
Repetition (loop)
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23. SEQUENCE Display “Enter Name” Input name Display “Hello “ name
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24. SELECTION (branch) IF Condition THEN Statement1 ELSE Statement2 True
. . .
Statement2
False
If (num > 0)
Display “Positive”
Else
Display “Negative”
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25. LOOP (repetition) WHILE Condition DO Statement1 False . . . Condition
True
Statement
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26. SUBPROGRAM (function)
. . .
SUBPROGRAM1
SUBPROGRAM1
a meaningful collection
of SEQUENCE,
SELECTION, LOOP,
SUBPROGRAM
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27. Computing Profession Ethics
copy software only with permission from the copyright holder
give credit to another programmer by name whenever using his/her code
use computer resources only with permission
guard the privacy of confidential data
use software engineering principles to develop software free from errors
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28. As proposed by the project sponsor.
                                  
                                   
As proposed by the project sponsor.
As specified in the project request.
As designed by the senior analyst.
                                    
                                 
As produced by the programmers.
As installed at the user's site.
What the user wanted.
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29. Step 1:Analysis Define the Problem
IPO
1. Input: Determine what is given
=>nouns, adjectives
2. Output: Determine what is required
3. Processing: Determine the transformations needed,actions needed to produce the required output
=>verbs, adverbs
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30. variables Input and output data Nouns Naming convention No spaces
Meaningful names
Usually begin with lowercase
Examples: roomWidth, numPeople, studentName
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31. Example 1 Read three numbers, add them together and print the total.
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32. 1. Identify inputs Underline nouns
Read three numbers, add them together and print the total.
Break up several values into separate variables
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33. 1. Identify inputs fill Input column first
Read three numbers, add them together and print the total.
Break up several values into separate variables
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34. 2. Identify outputs output column next
Read three numbers, add them together and print the total.
Break up several values into separate variables
No verbs here
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35. 3. Processing-Define processing steps by bolding verbs
Read three numbers, add them together and print the total.
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36. Each verb is a process step
Read three numbers, add them together and print the total.
Hint: Usually follows: input, process, output
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37. Step 3: define list of actions
Read three numbers, add them together and print the total.
Hint: Use verbs
these steps usually involve the input and output defined in step 1
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38. Example 2:
Write a program to prompt the operator for the maximum and minimum temperature readings on a particular day, accept those readings as integers, and calculate and display on the screen the average temperature.
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39. Example 2:
Write a program to prompt the operator for the maximum and minimum temperature readings on a particular day, accept those readings as integers, and calculate and display on the screen the average temperature.
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40. Example 2:
Write a program to prompt the operator for the maximum and minimum temperature readings on a particular day, accept those readings as integers, and calculate and display on the screen the average temperature.
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