Page 140 - Open Soource Technologies 304.indd

Event Driven Programming

ByVal curEarnings As Double) As Double
‘Calculate Social Security benefits tax and Medicare tax
‘for a single pay period in 2005
Dim socialSecurityBenTax, medicareTax As Double
If (ytdEarnings + curEarnings) <= 90000 Then
socialSecurityBenTax = 0.062 * curEarnings
ElseIf ytdEarnings < 90000 Then
socialSecurityBenTax = 0.062 * (90000 - ytdEarnings)
End If
medicareTax = 0.0145 * curEarnings
Return socialSecurityBenTax + medicareTax
End Function
[Run, type 12345.67 and 543.21 into the top two text boxes, and press the button. The following
is displayed in txtTax.]
$41.56

Comments
1. Constructs in which an If block is contained inside another If block are referred to as nested
If blocks.
2. Some programs call for selecting among many possibilities. Although such tasks can be
accomplished with complicated If blocks, the Select Case block (discussed in the next
section) is often a better alternative.

Write a program by using If-else block.

6.3 Do While Loops

A loop, one of the most important structures in Visual Basic, is used to repeat a sequence of
statements a number of times. At each repetition, or pass, the statements act upon variables
whose values are changing.
The Do loop repeats a sequence of statements either as long as or until a certain condition is true.
A Do statement precedes the sequence of statements, and a Loop statement follows the sequence
of statements. The condition, preceded by either the word “While” or the word “Until”, follows
the word “Do” or the word “Loop”. When Visual Basic executes a Do loop of the form
Do While condition
statement(s)
Loop
It first checks the truth value of condition. If condition is false, then the statements inside the
loop are not executed, and the program continues with the line after the Loop statement. If
condition is true, then the statements inside the loop are executed. When the statement Loop is

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