How our brains workAnd how it ties in to programming

and arrays

StorageSorting

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

53 32 81

Your brain contains the information (the Algorithim, if you like)To do stuff with these numbers.

You could add the numbersSort the numbers from smallest to largest.

How do we make a computer sort numbers?

53 32 81

SORT

32……53…….81

Programming codePut behind this to sort!

For instance.

Declare variables 1 2 and 3For 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 couldSIT STILLWALKRUNSWALLOWSINGTALKTHINK ABOUT YOUR EX BOYFRIENDTHINK OF A PLAN TO KILL Person XEAT SOMETHING that is in your pocketCLIMB A TREE

SIT STILLWALKRUNSWALLOWSINGTALKTHINK ABOUT YOUR EX BOYFRIENDTHINK OF A PLAN TO KILL Person XEAT SOMETHING that is in your pocketCLIMB 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 SpoonIf food looks edible

Else

If Food tastes nice

Else

Lift Spoon

Put spoon down

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 integeri=1

While I <10 theni*2= answer

Declare i as integeri=1

Repeati * 2 = answer

Until i=10

Dim i as integerFor i = 1 to 10

i= i*2Next 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 functionThat 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?

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

RecursionModule 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 = 1Return 1 elseFunction = 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

60 40

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 3

100Your 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

• 1• 2• 3• 4• 5• 6• 7• 8• 9

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#dRemember the 9 numbers

THIS IS CALLED AN ARRAY

(lots of variables)

Array counting up

0 1 2 3 4 5 6 7 8

1 2 3 4 5 6 7 8 9

Index number