paper 2

• INTEGER


  0-9 without decimal e.g. 95, 94, 93, 21
• REAL


  0-9 with decimal e.g. 95.1, 101.0, 9.3, 1.5
• STRING


  Alphabets, Numbers, Symbols
• CHAR


  Single character e.g. 'P', "A"
• BOOLEAN


  2 comparison values: True, False
• Appropriate data types for variables


  • INTEGER
  • STRING
  • CHAR
  • BOOLEAN
  • REAL
• Data Identifier Table


  Contains list of variable names and their descriptions, data types
• Algorithm


  Sequence of steps/instructions to implement a task/solution to a problem
• Stages of Algorithms


  • Input
  • Process
  • Output
• Features to make code easier to read and understand


  • Indentation
  • Blank lines
  • Capitalization of keywords
  • Sensible Variable Names
  • Comments
  • Pretty print
• Source Code


  Solution/design/algorithm expressed in high level language
• Object Code


  Produced by the compiler during translation stage, not produced by interpreter
• Pseudocode


  Uses keywords and identifiers to describe an algorithm without following the syntax of a particular programming language
• Flowchart


  Pictorial or graphical representation of a program in a flow
• 4 Basic Types of Constructs


  • Assignment
  • Sequence
  • Selection
  • Repetition/Iteration
• Assignment


  A value is given a name (identifier) or the value associated with a given identifier is changed
• Sequence


  A number of steps are performed one after the other
• Selection


  Under certain conditions, some of the steps are performed, otherwise no or different steps are performed
• Repetition/Iteration


  A sequence of steps is performed a number of times, also known as Looping
• Repetition Statements


  • For...To...Next (count-controlled loop)
  • While...Do...Endwhile (Pre conditional loop)
  • Repeat...Until (Post-conditional loop)
• Programming Constructs


  • Assignment
  • Sequence
  • Selection
  • Repetition
• Identifier


  Constant, Variable, Arrays
• Constant


  Value cannot be changed accidentally during execution of program
• Variable


  Stores a value that can change during execution
• Array


  A list of items of the same data type stored under a single name
• Data Verification


  Checking that data has not changed during transfer/input to a computer
• Data Verification Methods


  • Double Entry
  • Parity Check
  • Checksum
• Data Validation


  Checking that data meets certain criteria
• Data Validation Checks


  • Range checks
  • Presence check
  • Length check
  • Format check
  • Character check
  • Type check
• Types of Test Data


  • Normal Data (within range, accepted)
  • Abnormal Data (out of range, rejected)
  • Extreme Data
  • Boundary Data
• Features of a Program


  • Function/Procedure
  • Sequence
  • Iteration
  • Selection
  • Parameters
  • Variable
  • Logic Operation
• Integrated Development Environment (IDE)


  Combines all the features and tools needed by a software developer
• Features of an IDE


  • Pretty Print
  • Automatic Indentation
  • Syntax checking
  • Highlights any undeclared variable
  • Type checking
• Methods to find errors


  • Dry run trace table
  • Breakpoint: Run the code to set point to find error
  • Variable watch: Checks the content of variable at specific points
  • Execute the code line by line (Stepping)
• Stages of Program Development Cycle


  • Analysis
  • Design
  • Coding
  • Testing
  • Maintenance
• Editor


  Produces the source code in high level language
• Translator


  Converts source code into object code
• Debugger


  Used to test the program/detect errors
• Development Models


  • Waterfall Model
  • Iterative Model
  • Rapid Application Development
• Waterfall Model


  • Linear, each stage is completed before the next is begun
  • Well documented
  • Low customer involvement (only at start and end of process)