At the end of this lab you should be able to:

- Design interface on your own.
- Construct logical statements.
- Writing conditional if/else statement(s).
- Use the input box function to read input.
- Writing program statements using loops.

In this lab, you will do a series of small activities similar to Lab 06 designed to give you more exercise and practice in writing loops. By now you should be familiar with designing interfaces, working with variables and writing simple if/else statements. These activities will further test your ability in constructing logical statements and using them as control conditions in the loop.

Pre-Lab

i. Read the description of each activity carefully and thoroughly so that you understand what the problem is about i.e. what are the requirements and possible solutions for the given problem.

ii. Once you understand each activity requirement(s), then try to do a few examples on paper as to ascertain what your application output may be.

iii. Then design the interface keeping in mind what the user needs to input into the application; tasks that the program needs to perform and what needs to be displayed as output.

Activity 1: Sum of Series II

Create a Visual Basic Windows application to calculate the following series:

1 + 1/3 +1/5 + 1/7 + 1/9 +.........+ 1/n

Activity 1 and modify it accordingly.

Activity 2: Even Numbers

Create a Visual Basic Windows application that will use a Do While loop to print or display even numbers between 1 and 10. Have a command button on your interface which when clicked should simply display the even numbers in a label or a MsgBox control. There is no other interaction between the user and this application.

Activity 3: Divisible by 5

Create a for loop that will enumerate 50 times from 50 to 1. If the counter is divisible by 5, display the value of the counter in a label. Have a command button on your interface as well to initiate the process. The final outcome will be a label that will show all numbers between 50 and 1 that are divisible by 5. You may use a MsgBox to display the application results.

Activity 4: Powers of 2

Computers use the binary number system, which is based on powers of 2. Create a Visual Basic Windows application that displays the positive powers of 2. Have a command button on your interface which when clicked displays an input box that the user will use to enter the exponent (an integer). You program should then calculate and display 2 to that exponent in a label or MsgBox with the appropriate formatting.

The following algorithm may help you.

Read exponent from input box.

Convert exponent to integer

Calculate 2 to the exponent * Display result

In this activity, to calculate 2 to the exponent, do not use the arithmetic operator (^). Instead write a loop to repeat the loop ‘exponent' number of times with each pass multiplying the result by 2. For example, if exponent entered was 3 then the following loop calculates the value of 2 to the power 3.

Dim intCount As Integer = 0

Dim dblResult As Double = 1; ' why is it important to ' initialize this variable to 1?

Do While intCount < intExponent dblResult = dblResult * 2.0

intCount = intCount + 1

Loop