Select Case...End Select - VB6 Sample Program Part 2

This posting is continuation of previous posting "Select Case...End Select - VB6 Sample Program Part 1". In the previous posting you have designed a program interface like below image, and you have saved it.


Now, let's writing the program coding for the above program design.

Double click cmdCalBonus button to create sub cmdCalBonus_Click()

Write down below program coding in the cmdCalBonus_Click() area

    Select Case Val(txtSalQty.Text)
        Case 1 To 2
            txtBonus.Text = "2%"
        Case 3, 4
            txtBonus.Text = "3%"
        Case 5 To 6
            txtBonus.Text = "4.5%"
        Case 7 To 8
            txtBonus.Text = "6.5%"
        Case 9
            txtBonus.Text = "10%"
        Case Else
            txtBonus.Text = "15%"
    End Select
    txtBonusAmt.Text = Val(txtSalQty.Text) * Val(txtPriceUnit.Text) * _
                       Val(Left(txtBonus.Text, Len(txtBonus.Text) _
                       - 1)) / 100

At the end, your program will look like below listing:

Private Sub cmdCalBonus_Click()
    Select Case Val(txtSalQty.Text)
        Case 1 To 2
            txtBonus.Text = "2%"
        Case 3, 4
            txtBonus.Text = "3%"
        Case 5 To 6
            txtBonus.Text = "4.5%"
        Case 7 To 8
            txtBonus.Text = "6.5%"
        Case 9
            txtBonus.Text = "10%"
        Case Else
            txtBonus.Text = "15%"
    End Select
    txtBonusAmt.Text = Val(txtSalQty.Text) * Val(txtPriceUnit.Text) * _
                       Val(Left(txtBonus.Text, Len(txtBonus.Text) _
                       - 1)) / 100
End Sub

Let's test your program to check whether it's correct or not.

Click Start button on your VB toolbar

Type a number (for example 5) on your textbox with label Your Sales Quantity

Type a number (for example 100) on your textbox with label Price Unit (USD)

And finally click Calculate Bonus button

Notice what happen on your program, what's the result?

According to the Bonus Table if Sales Quantity = 5, so the Bonus Percentage should equal to 4.5%. So the Bonus Amount = 5 X 100 X 4.5 / 100. And the result is 22.5. So your program should like below screenshot.


Now I'll explain how the program works.

When you type 5 in the Your Purchase Quantity, then type 100 in the Price Unit (USD), and click Calculate Bonus button, so the cmdCalBonus_Click() executed.

Then this statement "Val(txtSalQty.Text)" will convert text "5" into number 5

Then in Select Case.. defined that txtBonus.Text is "4.5%" according to the Sales Quantity => 5

Then program executes below statement:

    txtBonusAmt.Text = Val(txtSalQty.Text) * Val(txtPriceUnit.Text) * _
                       Val(Left(txtBonus.Text, Len(txtBonus.Text) _
                       - 1)) / 100

Mybe you think that this is a complex statement. But in fact it's just a simple statement.
Val(txtSalQty.Text) convert text "5" into number 5
Val(txtPriceUnit.Text) convert text "100" into number 100

Because txtBonus.Text = "4.5%" (this is a text) so:
Len(txtBonus.Text) will return 4, and Len(txtBonus.Text) - 1 will return 3
Left(txtBonus.Text, Len(txtBonus.Text) - 1) equals to Left("4.5%",4-1) will return "4.5"
Then Val(Left(txtBonus.Text, Len(txtBonus.Text) - 1)) equal to Val("4.5") will return number 4.5

So the above formula will equal to:
txtBonusAmt.Text = Val("5")*Val("100")*Val(Left("4.5%",Len("4.5%")-1))/100
<=> txtBonusAmt.Text = 5 * 100 * 4.5 / 100
<=> txtBonusAmt.Text = 22.5

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