1. Mark Dixon Page 1 04 – Data Types

2. Mark Dixon Page 2 Admin: On-line Quiz

3. Mark Dixon Page 3 Questions: Expressions a)What is the result of: 10 * Int(3.1973265765) b)How many functions are in the following: Int(12.472) * Sqr(9) + 8 / 2 c)How many operators are in the following: Int(12.472) * Sqr(9) + 8 / 2 d)Write an expression to: divide 15 by 3 and multiply the result by 6 30 2 3 (15 / 3) * 6

4. Mark Dixon Page 4 Session Aims & Objectives Aims –to introduce the idea of types of data Objectives, by end of this week’s sessions, you should be able to: –recognise different types of data numeric string (text) –correct errors relating to data types

5. Mark Dixon Page 5 Example: AddNum v1 Add Numbers Sub btnAdd_OnClick() lblResult.InnerText = txtNum1.Value + txtNum2.Value End Sub Doesn't work!

6. Mark Dixon Page 6 Types of Information Numeric (numbers)29 (integer/whole) 56.23 (real/decimal) String (text)"Hello there!" "BOO" Pictures (numbers) Sound (numbers)

7. Mark Dixon Page 7 AddNum problem The + operator works with: –numbers, and –text 23 + 16 39 "23" + "16" "2316" double quotes enclose text Text input boxes store text: txtNum1.value + txtNum2.value We need to convert text to numbers

8. Mark Dixon Page 8 String Functions CInt("63") convert to integer result is 63 Left("boo",2) left stringresult is "bo" Right("hello",3) right stringresult is "llo" Mid("hello",2,3) middle stringresult is "ell" Len("S Smith") lengthresult is 7 Space(5) spacesresult is " "

9. Mark Dixon Page 9 String Expressions

10. Mark Dixon Page 10 String Expressions & Errors "What is " & txtN1.Value & " times " "What is twice " txtN1.Value & "?" "What is 6 minus " & & txtN1.Value & "?" "This is a number & txtN1.Value data operator data operator ERROR! missing data ERROR! missing operator ERROR! missing "

11. Mark Dixon Page 11 Questions: String Expressions a)What is the result of: Mid("what is the time?", 3, 4) b)What is the result of: Left("bob", 2) & Right("sal", 1) c)Write an expression to: convert "16" to a number d)Write an expression to: give the first two letters of "Mr John Smith" "at i" "bol" CInt("16") Left("Mr John Smith", 2)

12. Mark Dixon Page 12 Example: AddNum v2 Add Numbers Sub btnAdd_OnClick() lblResult.InnerText = CInt (txtNum1.Value) + CInt (txtNum2.Value) End Sub

13. Mark Dixon Page 13 Example: Sound Sound <object id="sndPlayer" classid="clsid:6BF52A52-394A-11d3-B153-00C04F79FAA6" style="width:0px; height:0px;"> Sub btnFart_onclick() sndPlayer.url = "Fart.wav" End Sub

14. Mark Dixon Page 14 Nested functions nested functions (one inside another): Right(Left("Hello there", 5), 2) do what is in the brackets first Right(Left("Hello there", 5), 2) = Right( "Hello", 2) = "lo"

15. Mark Dixon Page 15 Humans vs. Computers Humans and Computers work very differently Humans –declarative (goals): flexible sequence –intelligent: adaptive, questioning, rational –instinctive (without conscious thinking) –easily deal with incomplete and incorrect data –error prone (especially mundane repetitive tasks) Computers –procedural / algorithmic: fixed sequence –do exactly what they are told –cannot deal with errors –no imagination or creativity

16. Mark Dixon Page 16 Algorithms algorithm: step-by-step sequence of instructions, to solve a problem it describes how input data is to be processed in order to produce a desired output recipe –ingredients (similar to data) –method (is a type of algorithm)

17. Mark Dixon Page 17 Algorithms Making a cup of tea: 1. Fill the kettle with water 2. Plug the kettle in 3. Switch the kettle on 4. Wait for the kettle to boil 5. Put water in cup 6. Put a tea bag into the cup 7. Add sugar to the cup 8. Add milk to the cup 9. Stir 10. Take the tea bag out

18. Mark Dixon Page 18 What vs. How problem solving –known problems (remember solution) –unfamiliar problems (creative process, imagination) what vs. how: –What: increase value of a text box by 1 –How: read the current value add 1 put the result back in the text box For example: swap, search, sort

19. Mark Dixon Page 19 Example: Swap v1 Swap Sub btnSwap_onclick() txtA.value = txtB.value txtB.value = txtA.value End Sub put txtB into txtA put txtA into txtB does not work!

20. Mark Dixon Page 20 Example: Swap v1 (why?)

21. Mark Dixon Page 21 Example: Swap v2 Swap Sub btnSwap_onclick() txtTemp.value = txtA.value txtA.value = txtB.value txtB.value = txtTemp.value End Sub put txtA into temp put txtB into txtA put temp into txtB works!

22. Mark Dixon Page 22 Example: Swap v2 (Why?)

23. Mark Dixon Page 23 Example: Student Loan (Analysis) What: Calculate annual student load repayment from salary How: Algorithm: –read annual salary –deduct £15000 –calculate 9% –display result

24. Mark Dixon Page 24 Example: Student Loan (Design) When Calculate button is clicked: –read annual salary text box –deduct £15000 –calculate 9% –put result in paragraph Test Data: InputProcess Output –£1500015000-15000*0.09 =£0 –£1600016000-15000*0.09 =£90

25. Mark Dixon Page 25 Concrete vs. Abstract code we have: –pixelLeft –pixelTop right = left + width middle = left + (width / 2) concrete vs. abstract code: picBall.style.pixelLeft = 400 picBall.style.pixelLeft = document.body.clientWidth / 2 first one only works when the window width is 800

26. Mark Dixon Page 26 Generating Assignment Code put "Hello" into txtA txtA.value = "Hello" get txtA and join it with txtB, and put the result in parRes parRes.innerText = txtA.value + txtB.value put into txtNum2, the result of multiplying txtNum1 by 2 txtNum2.innerText = txtNum1.value * 2

27. Mark Dixon Page 27 Questions: Assignment What is the code for: –put 0 into the pixelLeft property of picHouse –increase the pixelTop property of picHouse by 5 –decrease the pixelTop property of picCar by 9 picHouse.style.pixelLeft = 0 picHouse.style.pixelTop = picHouse.style.pixelTop + 5 picCar.style.pixelTop = picCar.style.pixelTop - 9

28. Mark Dixon Page 28 Errors txtTemp.value = "" + 5 type mismatch (cannot add "" to 5) txtTemp.value = "7" + 5 OK – VB converts "7" into 7 automatically

29. Mark Dixon Page 29 Example: Text Shift Text Shift Sub Window_OnLoad() parH.innertext = "Hello There" & Space(100) Window.SetInterval "TextShift", 50 End Sub Sub TextShift() parH.innertext = Mid(parH.innertext,2) & Left(parH.innerText,1) End Sub

30. Mark Dixon Page 30 Tutorial Exercises: AddNum LEARNING OBJECTIVE: use a function to convert string (text) to integer (number) data Task 1: get the addnum examples (v1 and v2) working

31. Mark Dixon Page 31 Tutorial Exercises: Swap LEARNING OBJECTIVE: use an algorithm to solve a problem Task 1: get the swap examples (v1 and v2) working Task 2: change v2 of the swap page so that the temporary text box is hidden

32. Mark Dixon Page 32 Tutorial Exercises: Student Loan LEARNING OBJECTIVE: implement an algorithm in code Task 1: Create the user interface (page design) for the Student Loan example (from the lecture), using HTML tags (you will need a text box, a button, and a paragraph). Task 2: Add code that implements the following algorithm: When the Calculate button is clicked: –read annual salary text box –deduct £15000 –calculate 9% –put result in paragraph Task 3: Modify your program so that it calculates and displays monthly income and repayment amounts (as well an annual).

33. Mark Dixon Page 33 Tutorial Exercises: Text Shift LEARNING OBJECTIVE: develop and implement an algorithm to solve a problem use string manipulation functions, and sound Task 1: get the Text Shift example (from the lecture) working Task 2: modify your program so that the text goes the other way. Task 3: modify your program so that a noise is made when the user moves the mouse over the text.