CMPT 110 MIDTERM OCTOBER 18, 2001

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1 CMPT 110 MIDTERM OCTOBER 18, What will be displayed when the command button is clicked? 7% Level of difficulty 7 (out of 10) Assume there is a command button called cmdbutton Assume there is a picturebox called picoutput Private Sub cmdbutton_click() Dim x As String, y As String x = "tin" y = "can" Call Swap(x, y) picoutputprint x; " "; y Sub Swap(x As String, ByVal y As String) Dim temp As String temp = x x = y y = temp can can 1 What will be the output of following program when the command button is clicked? 7% Level of difficulty 5 Assume there is a command button called cmdbuttonassume there is a picture box called picbox Private Sub cmdbutton_click() Dim num as Single num = 10 Do While num > 1 picboxprint num; num = num - 3 Loop What is wrong with the following Do While loop? What will be the result of the problem with this loop? Level of difficulty 5 7% index = 1 Do While index <> 10

2 picboxprint "Hello" index = index + 2 Loop It is an infinite loop 1 The following is an infinite loop Rearrange the statements so that the loop will terminate as intended 7% Dim x as integer Assume there is a picturebox called picbox Level of difficulty = 5 x = 0 Do picboxprint x Loop Until x > 13 x = x + 2 Move the last statement one line up, before the Loop Until statement 1 How many times will HI be displayed when the following lines are executed? 7% Level of difficulty = 5 Assume there is a picture box picbox Dim c as integer c = 12 Do picboxprint "HI" c = c + 3 Loop Until c >= Given the following partial program, how many times will the statement 7% Level of difficulty = 7 picboxprint j, k be executed? Assume there is a picture box picbox Dim j, k as integer For j = 1 To 4 For k = 2 To 10 Step 3 picboxprint j, k Next k Next j 12 times

3 1 What should be the (approximate) output of the following program segment? 7% Do not try to calculate the actual output Just explain the significance of what this code is doing What do you expect the output to be? Difficulty = 8 Assume there is a picturebox called picboxdim x, k,y as integer For k = 1 To 1000 x = Rnd y = Rnd If x > y Then count = count + 1 End If Next k picboxprint count Approximately You are given the code below: 10% What is the content of the Text1 textbox after the user clicks the cmdgo command button? How many times is the math function executed? What is the value of math(4)? Assume there is a textbox called Text1 Private Function math(parameter as Integer) as Integer if parameter = 1 then math = 1 else math = parameter + math(parameter - 1) end if end function Private Sub cmdgo_click() Text1text = math(4) 10

4 9 Replace the following FOR loop by a WHILE loop Write a code segment, not pseudocode, that does the same thing Dim Ibegin, Iend, Iincrement as integer For I = IBegin To IEnd Step Iincrement loop body Next I In the above loop, we do not know if any of the set {IBegin, IEnd, Iincrement} is positive or negative (Assume that the set makes sense, however, and Iincrement is negative if IBegin > IEnd) 10% Ans: I = IBegin While ((IBegin > IEnd And I >= IEnd) Or (IBegin <= IEnd And I <= IEnd)) loop body I = I + Iincrement Wend 10 You are to write code that declares an array and which (1) reads 20 integer test scores into the array from a file and (2) counts the number of scores greater than or equal to 70 and prints it Ans: 'Declare array of 20 Dim myarray(1 To 20) As Integer 15% Private Sub Command1_Click() 'Declare variables Dim i As Integer 'Counter Dim counter As Integer 'Count >=70 Dim filenumber As Integer filenumber = FreeFile 'Open the file for input Open "D:\gradestxt" For Input As filenumber 'Initialize counter to zero counter = 0 'Loop exactly 20 times For i = 1 To 20 Step 1

5 'Read from file 'Store in array Input #filenumber, myarray(i) 'Check for >= 70 If myarray(i) >= 70 Then 'Update counter counter = counter + 1 End If Next i 'Close the file Close filenumber 'Display result Picture1Print "Count is " & counter '(Msgbox is acceptable too) 11 You are given the following code segment, with a call to a procedure called ComputeDifference The procedure ComputeDifference takes as input the array A, and produces as output the array D The array D contains the difference between consecutive elements of the array A For example, if A has 1, 3, 6, 8, 5, 15 then D should contain 2, 3, 2, -3, 10 In general, D(i) = A(i+1) - A(i), and the array D contains one less element then array A Dim A(1 To 20) As Integer Dim D() As Integer code that computes the values in array A Call ComputeDifference(A(), D()) You are to write the procedure ComputeDifference Make sure your procedure is general and works even if array A is declared to have a size other than 20 20% Private Sub ComputeDifference(intA() as Integer, intd() as Integer) Dim i as Integer ReDim intd(lbound(inta) To UBound(intA)-1) For I = LBound(intD) to UBound(intD) IntD(i) = inta(i + 1) - inta(i) Next i

Function: function procedures and sub procedures share the same characteristics, with

Function: function procedures and sub procedures share the same characteristics, with one important difference- function procedures return a value (e.g., give a value back) to the caller, whereas sub procedures