How our brains work And how it ties in to programming and arrays Storage Sorting Algorithms Etc…

What is computing? Computing is about computers just as much as astronomy is about telescopes Computing is not just hardware etc.. It’s a science…

Why is it called computer science? Just because our brains do it automatically –doesn’t mean everything else will We study how our brains do things…and try and replicate that in an in-animate system.

Numbers on a visual screen presented to your brain Your brain contains the information (the Algorithim, if you like) To do stuff with these numbers. You could add the numbers Sort the numbers from smallest to largest.

How do we make a computer sort numbers? SORT 32……53…….81 Programming code Put behind this to sort! For instance. Declare variables 1 2 and 3 For i is 1 to 3 If 1 > 2 then move 1 to Right. Next i

Our brains do this automatically Much of computer science Is –copying the way the brain works Making a system –a computer –that can do what our brains do!

Algorithms in our brain (that resemble a sort program) At any given time, you can do a million different things, You could SIT STILL WALK RUN SWALLOW SING TALK THINK ABOUT YOUR EX BOYFRIEND THINK OF A PLAN TO KILL Person X EAT SOMETHING that is in your pocket CLIMB A TREE

SIT STILL WALK RUN SWALLOW SING TALK THINK ABOUT YOUR EX BOYFRIEND THINK OF A PLAN TO KILL Person X EAT SOMETHING that is in your pocket CLIMB A TREE

Take the simplest of processes like EATING

Eating Swallow Taste Chew Spit Chew Again Bite Transfer to Molars Swallow again Open Mouth Close Mouth Lift Spoon

Eating Swallow Taste Chew Spit Chew Again Bite Transfer to Molars Swallow again Open Mouth Close Mouth Lift Spoon If food looks edible Else If Food tastes nice Else Lift Spoon Put spoon down Bite Taste Swallow Spit

Eating If food looks edible Else If Food tastes nice Else Lift Spoon Put spoon down Bite Taste Swallow Spit

Use of Loops? Child genius –could recite timestables (up to 20) at age 4

Reciting timestables 2 times 1 is 2 2 times 2 is 4 And so on HOW DOES YOUR BRAIN DO THIS? Task: Recite your two timestable –starting at 1 and stop at 10.

Immediately The brain sets a START AND STOP i.e starts at 1 Stops at 10 This is a loop!

Three types of loops WHILE LOOPS REPEAT UNTIL LOOPS FOR LOOPS Declare i as integer i=1 While I <10 then i*2= answer Declare i as integer i=1 Repeat i * 2 = answer Until i=10 Dim i as integer For i = 1 to 10 i= i*2 Next i

Computers (in order to even remotely resemble our brains) need to be programmed. Algorithms are developed to do what we imagine is something very very simple

Algorithims will typically involve One or more of The FOUR MAIN programming constructs

What are the main programming constructs? SequenceSequence (sequential programming) just a whole load of STATEMENTS Iteration (loops –While, Repeat, For) Selection (if statements, case statements) Recursion –a very complex type of function That calls itself

What are loops –how do they work All loops have a start stop i.e they all have a STOPPING CONDITION.. Otherwise they would go on forever!

How many loops do you see here?

Have I correctly identified the start and stop of each loop?

Recursion Module Module1 Dim a As Integer = 3 Dim b As Integer = 3 Sub Main() add(a, b) Console.ReadLine() End Sub Function add(ByVal a, ByVal b) If a = 0 Then Return b Else add = (a - 1) + (b + 1) Console.WriteLine(add) End If End Function End Module

Recursion Function (x) If x = 1 Return 1 else Function = x - Function (x-1) x=3 What is the value returned by Function?

And what’s an Array? What is a variable? A variable is like a like a space you need to declare –so that the computer knows to set aside a block of space to store something that it may need to compute

If you are given two numbers 6040

Add those two numbers up now Number 1 Number 2 = Number 3

What is the capital of egypt?

What is the answer of the addition of those two numbers? = Number Your brain stored the number 100 somewhere! In a computer we call this storage the use of a VARIABLE

Say you had a whole load of numbers Instead of setting aside 9 blocks of space in Your head for these numbers you might set aside 1 BLOCK OF SPACE and call it “counting up” That way…whenever anyone said COUNTING UP You’d remember to count up from 1 to 9…and you#d Remember the 9 numbers THIS IS CALLED AN ARRAY (lots of variables)

Array counting up Index number