TIK 2O - Test #3

1. TIK 2O - Test #3 Loops, Debugging, Functions, Arrays, Software Development Process

2. Multiple Choice • D – infinite loop (K doesn’t change) 69% • D – Until stops when condition becomes true 69% • C – rectangle (x coordinate changes by 2, y coordinate changes by 3) 69% • D Max + 1 – include 0 50% • Sum  Sum = Sum + Item (sum is incremented every time) 85% • B Item  beside the For 85%

3. Multiple Choice (Con’t) • B – Integer  vbYes and vbNo represent numerical integer values 46% • C – runtime error  the error doesn’t happen until the input is entered 81% • A – logic error – it creates the variable, so you won’t know unless the output is incorrect 54% • C – diagonal – both x and y change 77%

4. Multiple Choice (Con’t) • A – used to identify the array element 77% • C – control arrays start with an index of 0 92% • A – 2  one for the checkboxes, and one for the command buttons 100% • A – Problem Analysis – clarify the problem 85% • A – using price(1) whole time – first element … last value it is assigned is 20 69%

5. Multiple Choice (Con’t) • A – if the condition is met, it will not go inside the loop at all 77% • B – false – if a step is used, you can have it increment or decrement by whatever you want 69% • B – it has four elements  9, 10, 11, 12 92% • A – their index is different, but the name is exactly the same 81% • B – you are planning the major logic of your code as well as the comments 73%

6. Short Answer #1 (KU) Explain the difference between a conditional loop and a counted loop. 1 mark – conditional may execute any number of times – until / while a condition is being met 1 mark – counted loops execute a fixed number of times

7. Short Answer #2 (KU) What is a function? 1 mark - predefined section of code (the code is already created for you, we just use it) 1 mark - it performs a specific task (like rounding a number, or creating a random number)

8. Short Answer #3 (KU) Explain what is included in the Design – User’s Perspective of the Software Development Process 1 mark – sketch of the form 1 mark – description of program flow 1 mark – in simple, non technical language – anybody should be able to understand

9. Short Answer #4 (App) Do While not (a <> b) {statements} Loop Rewrite the following loop so that it’s meaning is the same, but it is logically simpler. Do While a = b {statements} Loop Do Until a <> b {statements} Loop

10. Short Answer #5 (App) Rewrite the following as a conditional loop 1 mark – initialize x 1 mark – proper condition 1 mark – increment x by 2 1 mark – proper order of statements For X = 10 to 20 Step 2 Total = Total + X + Y / 2 Next X X = 10 Do While X <= 20 Total = Total + X + Y / 2 X = X + 2 Loop

11. Short Answer #6 (App) What is the output of the following statements? 1 mark – calculate Vals(3) properly = 7 Vals(1) + 1 + Vals(2 – 1) =3 + 1 + Vals(1) = 3 + 1 + 3 = 7 1 mark – correct output - same line 3 4 7

12. Short Answer #7 (App) Write VB statements that would exchange the first and last elements of a Numbers array that has the following declaration. Dim Numbers (1 to 100) as Integer 1 mark – using only one temp variable 1 mark – properly switches Temp = Numbers(1) Numbers(1) = Numbers(100) Numbers(100) = Temp

13. Short Answer #8 (App) Trace the following code segment and sketch the output on a form. X = 1 Y = 5 Total = 0 Do Print “Loop 1” Y = Y – 2 Do While X < Y Print “Loop 2” Total = X * Y X = X + 1 Loop Loop While Y > 0 Print X; Y; Total;

14. Short Answer #8 (App) Trace the following code segment and sketch the output on a form. X = 1 Y = 5 Total = 0 Do Print “Loop 1” Y = Y – 2 Do While X < Y Print “Loop 2” Total = X * Y X = X + 1 Loop Loop While Y > 0 Print X; Y; Total; Loop 1 Loop 2 Loop 2 Loop 1 Loop 1 3 -1 6

15. Short Answer # 9 (TI) Explain how a control array could be used to simplify the following code segment. 1 mark – identifying that it is used for imgPic1, imgPic2, etc. 1 mark – use the random number as the index for the new imgPic(index) array 1 mark – random number needs to be 0 to 4, or use num – 1 as the index 1 mark – changes the code to 2 lines in length Num = Int((Rnd(5 – 1) + 1) imgGraphic.picture = imgPic(num-1).picture

16. Code Writing #1 1 mark – variable declarations 1 mark – initialize variable (for loop does this on its own) 1 mark – proper loop 1 mark – correct circles 1 mark – use scaleheight and scalewidth 1 mark – only use one loop Dim midx as Integer Dim midy as Integer Dim coordinate as Integer Coordinate = 0 Midx = me.scalewidth/2 Midy = me.scaleheight/2 Do until coordinate >= me.scaleheight circle (coordinate, midy), 0.5 circle (midx, coordinate), 0.5 coordinate = coordinate + 1 Loop

17. 1 mark – variable declarations (Average = single) 2 marks – use loop to calculate total and therefore average 2 marks – loop to count the number of students that are above average 1 mark – output (in statement form) 1 mark – initialize accumulator variables Code Writing #2 Dim x as Integer Dim total as Single Dim average as Single Dim Counter as Integer total = 0 For x = 1 to numstudent total = total + marks(x) Next x average = total / numstudent counter = 0 For x = 1 to numstudent if marks(x) > average then counter = counter + 1 end if Next x Print “There are “; counter; “students with a mark above average”