Chp-7&8

• Program Development Life Cycle

  • Analysis
  • Design
  • Coding
  • Testing
• Analysis


  • abstraction, decomposition of the problem, identification of the problem and requirements
• Design


  • decomposition, structure diagrams, flowcharts, pseudocode
• Coding


  • writing program code and iterative testing
• Testing


  • testing program code with the use of test data
• Variable


  A storage location. It is a named value that contains data that can be changed throughout the execution.
• Constant


  A storage location. It is a named location that contains a value that we don't want to change during the running of the program.
• Meaningful Names


  • The name should describe exactly the type of data stored in it.
• Variables


  • Use lower case letters at the start of variable names
  • Use either camel casing (without any white space, 1st letter is lower and every word starts with a capital letter [fileNotFound]) or snake casing (uses an underscore between words to create separation [build_docker])
• Constants


  • Use "Const" at the start of the name
  • Capitalise name
  • Use either camel casing or snake casing
• Constants


  • ConstTICKETPRICE = 25
  • Const_TICKET_PRICE = 25
• Array


  • Can be either a specified or unspecified length
  • Always use the square brakets
• Arrays


  • totalPrice = []
  • home_start_code = [0:4]
• Mathematical operators

  • ==
  • !=, <>

  <

  >

  >=

  <=
• Logical Operators


  • &&
  • ||
• Algorithm

  A set of instructions/steps/rules that are followed to solve a problem.
• Algorithm design


  • Pseudocode
  • Flowcharts
• Pseudocode


  • A method of expressing an algorithm design
  • Pseudocode is lines of instructions written in a language close to English but with common programming terms used where possible (selection and iteration etc)
  • Pseudocode is set out with the same structure as a programming language, but it is not a not programming language in itself
• Pseudocode


  • a non-proportional font is used throughout
  • all keywords (words used to describe a specific action e.g. INPUT) are written in capital letters
  • all names given to data items and subroutines start with a capital letter
  • where conditional and loop statements are used, repeated or selected statements are indented by two spaces
• Flowcharts

  • A graphical way of representing an algorithm design
  • A flowchart must have a clear start and finish (unless looping)
• Sequence


  In an algorithm, each instruction is written one after the other
• Selection or Conditional statements

  Creating the ability to choose the path to follow in a program
• Types of Selection


  • IF.. THEN .. ELSE .. ENDIF
  • CASE .. OF .. OTHERWISE .. ENDCASE
• IF.. THEN .. ELSE .. ENDIF

  • A logical condition is tested
  • A positive (true) outcome will result in the THEN statements of code being executed
  • A negative (false) outcome will result in the ELSE statements
• Purpose Of A Conditional Statement

  To allow different routes through a program dependent on meeting certain criteria
• Iteration (Looping)


  In a program there will be some instructions that need to be repeated. To repeat instructions we put them in a loop and this is referred to as iteration.
• Types of Iteration


  • FOR .. TO .. NEXT
  • REPEAT .. UNTIL
  • WHILE .. DO .. ENDWHILE
• FOR .. TO .. NEXT


  • Amount of iterations (times around the loop) is predetermined (fixed) at beginning of the loop
  • Already know how many iterations of the code is required
• REPEAT .. UNTIL


  • Condition/check is placed at the bottom of the loop, this is referred to as bottom testing (or a post condition)
  • At least one iteration of the loop will be executed
  • If an exit criteria has been met yet
• WHILE .. DO .. ENDWHILE

  • Condition is placed at the start of the loop, this is referred to as top testing (or a pre-condition)
  • Criteria has been met yet (to exit the loop)
• Procedures and Functions

  • A SUB-ROUTINE is a set of programming instructions for a given task that forms a sub-system, not the whole system. Sub-routines written in high-level programming languages are called 'procedures' or 'functions'
  • A procedure is a set of programming statements grouped together under a single name that can be called to perform a task at any point in a program
  • A function is a set of programming statements grouped together under a single name that can be called to perform a task at any point in a program. In contrast to a procedure, a function will return a value back to the main program
  • Parameters are the variables that store the values of the arguments passed to a procedure or function. Some but not all procedures and functions will have parameters.
• Counting


  Counting is used with repetition with the counter increased by 1 every time the loop is repeated.
• Totalling

  Totalling is used with repetition with the total updated every time the loop is repeated.
• Predefined Function

  a pre-programmed set of instructions that return a value.
• Library

  a store of pre-programmed instructions that can be imported into a program
• Predefined Procedures

  a pre-programmed set of instructions that do not return a value.
• Global Variable

  can be used by any part of a program - its scope covers the whole program.
• Local Variable

  can only be used by the part of the program it has been declared in - its scope is restricted to that part of the program.
• Array

  A data structure containing several elements of the same data type; these elements can be accessed using the same identifier name.
• Element

  An individual data location in an array.