Alice project 3 review

ALICE PROJECT 3 REVIEW


LOGIC STRUCTURE OF ALGORITHMS
	- Every computer is an algorithm - a step by step process
	- In modern OOP, each method is an algorithm
	- Algorithms are sequenced by default
	- steps in algorithm form a kind of sequential logic

THREE MAJOR LOGICAL STRUCTURES IN ALGORITHMS:
	- branching routines
	- loops
	- linear sequences (No branch or loops)

	These 3 elements are the building blocks for algorithms

FLOW CHART: a diagram that shows the structure of an algorithm
	- rectangles represent algorithm
	- diamond shaped boxes represents branching
	- Oval shaped boxes represents beginning and ends

LINEAR SEQUENCES:
	- clear starting and ending point
	- entry and exit conditions have to be clearly stated
		What conditions need to exist before the sequence starts
		What can we expect the situation when the sequence is finished
	- sequence of instructions must be complete
	- sequence of instructions need to be in the proper order
	- all instruction in the sequence must be correct and valid, a single mistake could cause the entire algorithm to fail

BRANCHING ROUTINE (SELECTION SEQUENCES):
	- occurs whenever the flow of instructions in a computer program splits into separate paths
	- 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)
	- there are 2 types of binary branching sequences:
		binary bypass: an instruction is either executed or passed
			Example: if <condition> do <instruction> else do <nothing>
		binary choice: one of two instructions, NOT both, is executed.
			Example: if <condition> do <instruction> else do <different instruction>
	MULTIPLE BRANCHING:
		- a series of If/Else instructions
		- it can always be rewritten as a series of nested binary branchings
		Example:	If <condition> do
					<instruction>
				elseif <condition> do
					<instruction>
				else do
					<instruction>

LOOPING SEQUENCES (REPETITION SEQUENCES):
	- in loops, word WHILE is used instead of IF
		Example: while <condition (true)> do <instructions>

		------[condition]---False--->
		  ^	   |
		  |	 True
		  |	   V
		  ---[instruction]

		It will keep doing the instructions until the condition becomes false
	- loops have conditions that controls whether or not the repetition sequence will be executed
	- a set of instructions to be repeated in a loop is called a body of the loop
	PRETEST LOOPS - if test comes BEFORE the body of the loop
	POSTTEST LOOPS - if test comes AFTER the body of the loop

		--------[test]---False--->
		  ^	   |
		  |	 True					PRETEST LOOP
		  |	   V
		  ---[instruction]

		--------[instruction]-->[test]---False--->
		    ^			  |
		    |			 True			POSTTEST LOOP
		    |_____________________|

	COUNT-CONTROLLED AND SENTINEL LOOPS:
		Major 4 parts:
		- Initialization: an instruction that sets the first value of the control variable
		- Test: looks at the control variable to see if the loop should be executed
		- Processing: instructions or set of instructions to be repeated in the loop
		- Update: changes the value of the control variable each time it goes through the loop

			Example:
			i = 1			[Initialization]
			while i < 5 do		[Test]
			say i			[Processing]
			i = i + 1		[Update]

BOOLEAN LOGIC
	The six different logical comparison operation in computer programming
		- A equal B
		- A does not equal B
		- A is less than B
		- A is greater than B
		- A is less than or equal to B
		- A is greater than or equal to B

	3 basic operations:
		AND:    Need 2 equal to be true
			true and true = true
			true and false = false
			false and true = false
			false and false = true
		OR:	anyone is true is true
			true or true = true
			true or false = true
			false or true = true
			false or false = false
		NOT:	opposite
			not true = false
			not false = true
MORE ABOUT:
	Using comments
		comments are a type of software documentation, it can help when programming
	The ACM
		Association for Computing Machinery: One of the oldest and most respected organizations for computer science professionals, educators, and students. (www.acm.org)
	Software diagrams
		Computer scientists and software engineers uses diagrams to describe a computer software