Software Development

1
Software Development

• Define the problem (Analysis)
• Plan the solution
• Code
• Test and debug
• Maintain and Document

2
Code

• Write program in a specified language
• editor - key in- create source program
• .cpp (if c is the language)
• compiling - create object program
• Syntax error
• .obj
• link - create executable
• .exe
• Run
• Logic errors
• Lab 1

3
Problem Analysis

• Problems Take one of the following tasks and
  write a set of instructions(a solution) so
  complete that another person could perform the
  task without asking questions
• Make a cup of cocoa
• Sharpen a pencil
• Decide which number is the largest from a group
  of three numbers
• Start a car(include directions regarding what to
  do if the car does not start
• Buy a soda from the soda machine

4
Problem Solving

• Identify, understand the problem
• Obtain additional information
• Read and reread to obtain additional information
• Alternatives
• List instructions that enable you to solve the
  problem by the selected method

5
Problem Solving

• Some problems require a series of actions or an
  algorithmic colution
• Exa. solving a complicated calculus program
• Alphabetizing 10,000 names
• Other problems require reasoning built on
  knowledge and experience heuristic solution
• Computers are better at algorithmic solutions
• Problems with problem solving
• Define problem incorrectly
• Don't identify a sufficient list of alternatives

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Analysis of the Problem

• 1. Determine what is given - input
• gtnouns, adjectives
• 2. Determine what is required - output
• gtnouns, adjectives
• 3. Determine the transformations
  needed(processing)
• -actions needed to produce the required output
• gtverbs, adverbs

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Example 1
Read three numbers, add them together and print
the total. Read three numbers, add them together
and print the total.
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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.
9
Structured Programming

• Control structures
• sequence
• selection or IF-THEN-ELSE
• repetition or looping
• subprograms
• Top Down Design
• Modularity

10
Design/Plan the solution

• Algorithm a step by step procedure for solving
  a problem
• All programs are implementations of algorithms
• subtasks - hierarchy chart
• logic
• flowcharts
• pseudocode
• test solution for correctness - trace

11
Algorithm

• Algorithm set of steps that defines how a task
  is performed
• Program set of instructions written in
  appropriate language
• Correctness
• efficiency

12
Pseudocode

• structured concise English statements used to
  state operations
•  language independent,no standard
•  use words and phrases that are in line with
  basic computer operations
•  

13
Pseudocode

• Write statements in simple English
• Write each instruction on a separate line.
• Use keywords and indentation for control
  structures.
• 4. Write instructions from top to bottom, with
  only one entry and one exit.

14
Pseudocode

•  1. Input - receiving information
•  keywords - read, get
•  Read - receive information from a record on a
  file
• Get - receive information from the keyboard.
•  Read student_name
• Get system_date
• Read number_1,number_2
• Get tax_code
•  use one verb followed by one or more nouns

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Pseudocode

• 2. Output
• putting information out
• put, output,display - screen
• print - printer
• write - file
• Print smaller.
• Print 'Program Completed'
• Write customer_record to file
• Output total_tax
• Display 'End of Data'

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Output continued

• Labels
• Print 'label' or Print "label"
•  statement inside quotes is printed as it appears
• Print 'x' // if x 5
• Yields x
• Print x
•  yields 5
•  Print 'X ' and x
•  yields X 5

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Pseudocode

• 3. Arithmetic
•  use name of the operation or algebraic symbol
•  add,subtract,multiply, divide, exponentiation
•   - /
•  x algebraic expression
• count count 1
• net pay hourly_pay_rate hours_worked
• sales_tax cost_price 0.10
• sales_tax price tax_rate

18
Pseudocode

• 4. Assignment - place information into a storage
  location
•  Initialize, Set - give variable initial value
• Save,Store - save info for later
•   //preferred
• y 3 note does not mean equality
• could involve calculation
• area length width
•   

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Assignment

• Examples
• counter 0
• Initialize counter to zero
• Set count to 1
• Initialize tot_accums to 0
• Set upper_limit to 100
• total_price cost_price sales_tax