VB1

Program 7a

In this exercise, you experiment with passing variables by value and by reference. Open the Passing Solution file. If necessary, open the designer window.

a. Open the Code Editor window and review the existing code. Notice that the strMyName variable is passed by value to the GetName procedure. Start the application. Cick the Display Name button. When prompted to enter a name, type your name and press Enter. Explain why the btnDisplay control’s click event procedure does not display your name in the lblName control. Stop the application.

b. Modify the btnDispaly control’s Click event procedure so that it passes the strMyName variable by reference to the GetName procedure. Save the solution and then start the application. Click the Display Name button. When prompted to enter a name, type “Justin Verlander” and press Enter. This time, “Justin Verlander” appears in the lblName control. Explain why the btnDisplay control’s Click event procedure now works correctly. Stop the application. Close the Code Editor window and then close the solution.

Program 7b

Create a Visual Basic Windows application. Use the following names for the solution and project, respectively: Planets Solution and Planets Project. Change the form file’s name to Main Form.vb. Change the forms name to frmMain. Create the interface shown in Figure 7-32. (I can’t show this image but the box is called “Weights on Other Planets” and it gives you the option to enter “Earth Weight” and then a combo box for “Weight on” with another box underneath that one. There is an exit button) The combo box should have the DropDownList style and contain the following planet names: Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto. When the user clicks a planet name, the application should convert the earth weight to the weight on that planet, and then display the converted weight in the label control. Use the Internet to research the formula for making the conversions. Save the solution and then start and test the application. Close the Code Editor window and then close the solution.

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Program 7c

See images Program 7c1 and Program 7c2 in the folder for this.

Chapter 7 Quiz (10 Questions)

1) Visual Basic allows you to specify that an argument in the Call statement is optional.

Question 1 options:

True

False

2) The computer automatically processes an event procedure when the event occurs.

Question 2 options:

True

False

3) An independent Sub procedure is a procedure that is independent of any object and event.

Question 3 options:

True

False

4) The number of arguments listed in the Call statement’s argumentList should agree with the number of parameters listed in the parameterList in the procedure header.

Question 4 options:

True

False

5) Math.Round(3.234, 2) returns the number 3.24.

Question 5 options:

True

False

6) Which of the following is a valid header for a procedure that is passed the number 9.75?

Question 6 options:

Private Function CalcSubtotal(ByVal intPrice As Integer) As Decimal

Private Function CalcSubtotal(ByRef intPrice As Integer) As Decimal

Private Function CalcSubtotal(ByVal decPrice As Decimal) As Decimal

Private Function CalcSubtotal(ByVal intPrice As Integer)

7) Which of the following is a valid Return statement?

Question 7 options:

dblNumber Return

Return dblNumber ByRef

Return ByRef dblNumber

Return dblNumber

8) As you do with list boxes, you use the Items collection’s ____ method to add an item to a combo box.

Question 8 options:

Insert

Add

New

Append

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9) A combo box’s ____ property contains the value that appears in the text portion of the control.

Question 9 options:

Add

Sorted

Text

List

10) Like the first item in a list box, the first item in a combo box has an index of ____.

Question 10 options:

0

1

2

3