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Alice project 3 review

By: Helium on Feb 25th, 2013  |  syntax: None  |  size: 4.27 KB  |  views: 68  |  expires: Never
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  1. ALICE PROJECT 3 REVIEW
  2.  
  3.  
  4. LOGIC STRUCTURE OF ALGORITHMS
  5.         - Every computer is an algorithm - a step by step process
  6.         - In modern OOP, each method is an algorithm
  7.         - Algorithms are sequenced by default
  8.         - steps in algorithm form a kind of sequential logic
  9.  
  10. THREE MAJOR LOGICAL STRUCTURES IN ALGORITHMS:
  11.         - branching routines
  12.         - loops
  13.         - linear sequences (No branch or loops)
  14.        
  15.         These 3 elements are the building blocks for algorithms
  16.  
  17. FLOW CHART: a diagram that shows the structure of an algorithm
  18.         - rectangles represent algorithm
  19.         - diamond shaped boxes represents branching
  20.         - Oval shaped boxes represents beginning and ends
  21.  
  22. LINEAR SEQUENCES:
  23.         - clear starting and ending point
  24.         - entry and exit conditions have to be clearly stated
  25.                 What conditions need to exist before the sequence starts
  26.                 What can we expect the situation when the sequence is finished
  27.         - sequence of instructions must be complete
  28.         - sequence of instructions need to be in the proper order
  29.         - all instruction in the sequence must be correct and valid, a single mistake could cause the entire algorithm to fail
  30.  
  31. BRANCHING ROUTINE (SELECTION SEQUENCES):
  32.         - occurs whenever the flow of instructions in a computer program splits into separate paths
  33.         - there must be a condition to determine which path the computer will follow each time the selection sequence is being executed (Binary branching splits in 2 paths, true or false)
  34.         - there are 2 types of binary branching sequences:
  35.                 binary bypass: an instruction is either executed or passed
  36.                         Example: if <condition> do <instruction> else do <nothing>
  37.                 binary choice: one of two instructions, NOT both, is executed.
  38.                         Example: if <condition> do <instruction> else do <different instruction>
  39.         MULTIPLE BRANCHING:
  40.                 - a series of If/Else instructions
  41.                 - it can always be rewritten as a series of nested binary branchings
  42.                 Example:        If <condition> do
  43.                                         <instruction>
  44.                                 elseif <condition> do
  45.                                         <instruction>
  46.                                 else do
  47.                                         <instruction>
  48.  
  49. LOOPING SEQUENCES (REPETITION SEQUENCES):
  50.         - in loops, word WHILE is used instead of IF
  51.                 Example: while <condition (true)> do <instructions>
  52.  
  53.                 ------[condition]---False--->
  54.                   ^        |
  55.                   |      True
  56.                   |        V
  57.                   ---[instruction]
  58.  
  59.                 It will keep doing the instructions until the condition becomes false
  60.         - loops have conditions that controls whether or not the repetition sequence will be executed
  61.         - a set of instructions to be repeated in a loop is called a body of the loop
  62.         PRETEST LOOPS - if test comes BEFORE the body of the loop
  63.         POSTTEST LOOPS - if test comes AFTER the body of the loop
  64.  
  65.                 --------[test]---False--->
  66.                   ^        |
  67.                   |      True                                   PRETEST LOOP
  68.                   |        V
  69.                   ---[instruction]
  70.  
  71.                 --------[instruction]-->[test]---False--->
  72.                     ^                     |
  73.                     |                    True                   POSTTEST LOOP
  74.                     |_____________________|
  75.  
  76.         COUNT-CONTROLLED AND SENTINEL LOOPS:
  77.                 Major 4 parts:
  78.                 - Initialization: an instruction that sets the first value of the control variable
  79.                 - Test: looks at the control variable to see if the loop should be executed
  80.                 - Processing: instructions or set of instructions to be repeated in the loop
  81.                 - Update: changes the value of the control variable each time it goes through the loop
  82.  
  83.                         Example:
  84.                         i = 1                   [Initialization]
  85.                         while i < 5 do          [Test]
  86.                         say i                   [Processing]
  87.                         i = i + 1               [Update]
  88.  
  89. BOOLEAN LOGIC
  90.         The six different logical comparison operation in computer programming
  91.                 - A equal B
  92.                 - A does not equal B
  93.                 - A is less than B
  94.                 - A is greater than B
  95.                 - A is less than or equal to B
  96.                 - A is greater than or equal to B
  97.  
  98.         3 basic operations:
  99.                 AND:    Need 2 equal to be true
  100.                         true and true = true
  101.                         true and false = false
  102.                         false and true = false
  103.                         false and false = true
  104.                 OR:     anyone is true is true
  105.                         true or true = true
  106.                         true or false = true
  107.                         false or true = true
  108.                         false or false = false
  109.                 NOT:    opposite
  110.                         not true = false
  111.                         not false = true
  112. MORE ABOUT:
  113.         Using comments
  114.                 comments are a type of software documentation, it can help when programming
  115.         The ACM
  116.                 Association for Computing Machinery: One of the oldest and most respected organizations for computer science professionals, educators, and students. (www.acm.org)
  117.         Software diagrams
  118.                 Computer scientists and software engineers uses diagrams to describe a computer software