Mark Dixon, SoCCE SOFT 131Page 1 04 – Conditional Execution.

Mark Dixon, SoCCE SOFT 131 Page 1

04 – Conditional Execution


Questions: Expressionsa) 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


Session Aims & Objectives• Aims

– to introduce the main concepts involved in getting the computer to act differently under different circumstances

• Objectives,by end of this week’s sessions, you should be able to:

– evaluate conditional expressions, and– implement decision trees in code


Example: AddNum v1<html> <head> <title></title> <script language="VBScript"> Sub btnAdd_OnClick() lblResult.InnerText = txtNum1.Value + txtNum2.Value End Sub </script> </head> <body> <input type="text" ID=txtNum1> <input type="text" ID=txtNum2> <input type="button" ID=btnAdd value="Add"> <p ID=lblResult> </body></html>

Doesn't work!


Types of Information• Numeric (numbers) 29

(integer/whole) 56.23 (decimal/real)

• String (text) "Hello there!""BOO"

• Pictures (numbers)

• Sound (numbers)


AddNum problem• The + operator works with:

– numbers, and

– text

• Text input boxes store text

23 + 16 39

"23" + "16" "2316"

double quotes enclose text


String Functions CInt("63") convert to integer result is 63

Left("boo",2) left string result is "bo"

Right("hello",3) right string result is "llo"

Mid("hello",2,2) middle string result is "el"

Len("S Smith") length result is 7

Space(5) spaces result is " "


String Expressions


String Expressions & Errors "What is " & txtN1.Value & " times "

"What is twice " txtN1.Value & "?"

"What is 6 minus " & & txtN1.Value & "?"

dataoperator

data data

operator

ERROR! missing data

ERROR! missing operator


Questions: String Expressionsa) What is the result of:

Mid("what is the time?", 3, 4)

b) What is the result of: "23" & "18" + Left("bob",1) + Right("sal",2)

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"

"2318bal"

CInt("16")

Left("Mr John Smith", 2)


Example: AddNum v2<html> <head> <title></title> <script language="VBScript"> Sub btnAdd_OnClick()

lblResult.InnerText = CInt(txtNum1.Value) + CInt(txtNum2.Value) End Sub </script> </head>

<body> <input type="text" ID=txtNum1> <input type="text" ID=txtNum2> <input type="button" ID=btnAdd value="Add"> <p ID=lblResult> </body></html>


Example: Text Shift<html> <head> <title>Text Shift</title> <script language="VBScript"> Sub Window_OnLoad() parH.innertext = parH.innertext & Space(100) Window.SetInterval "TextShift", 50 End Sub

Sub TextShift() parH.innertext = Mid(parH.innertext, 2) & Left(parH.innerText, 1) End Sub </script> </head>

<body> <p id="parH"> Hello There</p> </body></html>


Adaptive Behaviour• So far

– every statement always executed in sequence

• Often necessary for software to– change behaviour under different circumstances


Example: Multiplication TestSPECIFICATION

• User Requirements – A primary school teacher wants to test the

multiplication skills of her children.

• Software Requirements– Functional:

–display a multiplication question–allow the user to type a response–check the response and provide feedback

– Non-functionalshould be interesting, colourful, and easy to use


Example: Multiplication Test v1<html> <head> <title>Multiply</title> <script language=VBScript> Sub btnAns_OnClick() If txtAns.Value = 15 Then document.bgcolor = "yellow" lblComment.innertext = "Correct, well done!" Else document.bgcolor = "cyan" lblComment.innertext = "Sorry, try again" End If End Sub </script> </head> <body> <p>What is 5 times 3? <input type=text id=txtAns> <p><input id=btnAns type=button value=Check> <p id=lblComment> </body></html>


Example: Multiplication Test v1


Example: Multiplication Test v1


Example: Multiplication Test v1.1<html> <head> <title>Multiply</title> <script language=VBScript> Sub btnAns_OnClick() If txtAns.Value = 15 Then document.bgcolor = "yellow" lblComment.innertext = "Correct, well done!" sndFanfare.Play Else document.bgcolor = "cyan" lblComment.innertext = "Sorry, try again" sndFart.Play End If End Sub </script> </head> <body> <p><embed id=sndFanfare src=Fanfare.wav hidden=true autoplay=false> <embed id=sndFart src=Fart.wav hidden=true autoplay=false> What is 5 times 3? <input type=text id=txtAns> <p><input id=btnAns type=button value=Check> <p id=lblComment> </body></html>


If Then statements• Use the following syntax:

If condition Then statementblockEnd If

• For example:If txtAge.value < 21 Then document.bgColor = "Red"End If


If Then Else statements• Use the following syntax:

If condition1 Then statementblock-1Else statementblock-2End If

• For example:If txtAge.value Then document.bgColor = "Red"Else document.bgColor = "Blue"End If


Conditions & Relational Operators

• Conditions – expression, evaluates to:– true (stored as –1)

– false (stored as 0)

• contain relational operators:= is equal to> is greater than< is less than>= is greater than or equal to<= is less than or equal to<> is not equal to


Examples: Conditions• Using literals:

(34 = 34) (evaluates to true)(34 = 12) (evaluates to false)(34 > 4) (evaluates to true)(18 <=18) (evaluates to true)

• Using controls' properties:Assume that picMain.hSpace is 2300 (picMain.hSpace = 2300) (true) (picMain.hSpace = 2309 (false) (picMain.hSpace <> 189 (true) (picMain.hSpace > 1900 (true)


Logical Operators

• And True when both items are True(picMain.vSpace > 5) AND (picMain.vSpace < 35) (true)(picMain.vSpace < 10) AND (picMain.vSpace > 55) (false)(picMain.vSpace > 6) AND (picMain.vSpace < 23) (false)(picMain.vSpace >=6) AND (picMain.vSpace <= 23) (true)

• Or True when either item is True(picMain.vSpace = 23) OR (picMain.vSpace = 11) (true)(picMain.vSpace < 10) OR (picMain.vSpace > 55) (false)

• Not True when item is FalseNot (picMain.vSpace = 23) (false)

Use to join conditions (assume picMain.vSpace is 23):


Exercise: Conditions• What is the result of (picMain.hSpace is 5589):

(picMain.hSpace > 4400)

• What is the result (txtAge.value is 19, txtSalary.value is 10787):

(txtAge.Value < 21) AND (txtSalary.Value < 10787)

• Write an expression to check if:

picMain.hSpace is larger than 167

• Write an expression to check if:

picMain.vSpace is larger than picBall.vSpace

true

false

(picMain.hSpace > 167)

(picMain.vSpace > picBall.vSpace)


Example: Student Loan<html> <head> <title>Student Loan Repayment Calculator</title> <script language=VBScript> Sub btnCalc_OnClick() lblPayment.innertext = (txtIncome.value - 15000) * 0.09 End Sub </script> </head> <body> <center><font size=+2><b>Student Loan Repayment Calculator</b></font></center> <input type=text id=txtIncome> <input type=button id=btnCalc value=Calculate> <p id=lblPayment> </body></html>

SLC


Example: Student Loan (v2)<html> <head> <title>Student Loan Repayment Calculator</title> <script language=VBScript> Sub btnCalc_OnClick() If txtIncome.value > 15000 Then lblPayment.innertext = "£" & (txtIncome.value - 15000) * 0.09 Else lblPayment.innertext = "You pay nothing (£0.00)!" End If End Sub </script> </head> <body> <center><font size=+2><b>Student Loan Repayment Calculator</b></font></center> <input type=text id=txtIncome> <input type=button id=btnCalc value=Calculate> <p id=lblPayment> </body></html>


Example: Ball Char• Functional Decomposition

• Incremental Development

• Get ball char to bounce horizontally:– get ball char to appear on left of page– get ball char to move right on page (user click)– get ball char to move right on page automatically– get ball char to stop at end– get ball char to change direction


Example: Ball Char (v2)<html> <head> <title>Test</title> <script language="VBScript"> Sub window_OnLoad() window.SetInterval "MoveBallRight", 50 End Sub Sub MoveBallRight() picBall.hspace = picBall.hspace + 5 End Sub </script> </head> <body bgcolor="#00ff00"> <p><img id=picBall src="BallChar.jpg" hspace=0 vspace=11></p> </body></html>


Example: Ball Char (v2.1)<html> <head> <title>Test</title> <script language="VBScript"> Sub Window_OnLoad() Window.SetInterval "MoveBallRight", 50 End Sub Sub MoveBallRight() If picBall.hSpace < Document.Body.ClientWidth Then picBall.hSpace = picBall.hSpace + 5 End If End Sub </script> </head> <body bgcolor="#00ff00"> <p><IMG id=picBall src="BallChar.jpg" hspace=0 vspace=11></p> </body></html>


Example: Ball Char (v2.2)<html> <head> <title>Test</title> <script language="VBScript"> Sub Window_OnLoad() Window.SetInterval "MoveBallRight", 50 End Sub Sub MoveBallRight() If picBall.hspace < (document.body.clientwidth - picBall.Width) Then picBall.hspace = picBall.hspace + 5 End If End Sub </script> </head> <body bgcolor="#00ff00"> <p><IMG id=picBall src="BallChar.jpg" hspace=0 vspace=11></p> </body></html>


Example: Ball Char (v2.3)<html> <head> <title>Test</title> <script language="VBScript"> Sub Window_OnLoad() Window.SetInterval "MoveBallRight", 50 End Sub Sub MoveBallRight() If (picBall.hspace + 5) < (document.body.clientwidth - picBall.Width) Then picBall.hspace = picBall.hspace + 5 End If End Sub </script> </head> <body bgcolor="#00ff00"> <p><IMG id=picBall src="BallChar.jpg" hspace=0 vspace=11></p> </body></html>


Example: Ball Char (v2.4)<<html> <head> <title>Test</title> <script language="VBScript"> Sub Window_OnLoad() Window.SetInterval "MoveBallRight", 50 End Sub Sub MoveBallRight() If (picBall.hspace + 5) < (document.body.clientwidth - picBall.Width) Then picBall.hspace = picBall.hspace + 5 Else Window.SetInterval "MoveBallLeft", 50 End If End Sub Sub MoveBallLeft() picBall.hspace = picBall.hspace - 5 End Sub </script> </head> <body bgcolor="#00ff00"> <p><IMG id=picBall src="BallChar.jpg" hspace=0 vspace=11></p> </body></html>>


Example: Ball Char (v2.5)• Bounce from side to side, with sound:


Tutorial Exercises: AddNum• LEARNING OBJECTIVE:

use function to convert string (text) to integer (number)

• Task 1: get the addnum examples (v1 and v2) working


Tutorial Exercises: Text Shift• LEARNING OBJECTIVE:

use string manipulation functions

• Task 1: get the Text Shift example (from the lecture) working


Tutorial Exercises: Initials• LEARNING OBJECTIVE:

use string manipulation functions

• Task 1: create a new site with two text boxes (surname and forenames), and a button (initials). When the button is clicked the first character from each text box (i.e. the person's initials) should be displayed.


Tutorial Exercises: Multiplication• LEARNING OBJECTIVE:

use if statement to perform conditional execution

• Task 1: Get the Multiplication v1 and v1.1 examples (from the lecture) working.

• Task 2: Modify your program so that the text box is disabled after the answer is checked

• Task 3: Modify your program so that it makes a suitable sound when the user gets the answer right/wrong. Sound files are in the resources section of the web-site


Tutorial Exercises: Student Loan• LEARNING OBJECTIVE:


• Task 1: Get the Student Loan v1 and v2 examples (from the lecture) working.

• Task 2: Modify your program so that it calculates and displays monthly income and repayment amounts (as well an annual).


Tutorial Exercises: BallChar• LEARNING OBJECTIVE:


• Task 1: Get the BallChar example (from the lecture) working.You will need to work out the code for v2.5 – use the previous code for inspiration.

• Task 2: Modify your program so that the Ball Character blinks when the mouse moves over it

• Task 3: Modify your program to play a sound when the ball character is clicked

Mark Dixon, SoCCE SOFT 131Page 1 04 – Conditional Execution.

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