Basic VBScript for Elipse E3: Lesson 3 – Decision Commands

Command If…Else…ElseIf…End If

This command allows taking decisions during a script’s execution. The syntax is the following:

If condition Then
code that will be executed if the condition is true.
Else
code that will be executed if the condition is NOT true.
End if

Examples:

If Engine=0 Then
    Text=”Engine off”
Else
    Text=”Engine on”
End if
More than one condition can be verified in the same command:

If Then
    code that will be executed if condition1 is true.
Elseif Then
    code that will be executed if condition2 is true.
Elseif <condition3> Then
    code that will be executed if condition3 is true.
Else
    code that will be executed if none of the conditions is true.
End if

Examples:

If Engines=0 then
    Text=”Engines off”
Elseif Engines=1 then
    Text=”Engine 1 on”
Elseif Engines=2 then
    Text=”Engine 2 on”
Elseif Engines=3 then
    Text=”Engines 1 and 2 on”
Else
    Text=”Status error. Check the engines”
End if
Exercises:

1. Write the code for the following dialog boxes and display on a second message the user’s answer [(Yes or No) and (Retry or Cancel)].

Figure 9
Figure 10

2. Create a setpoint that only allows typing values.
3. By changing setpoint’s value, modify a rectangle’s color by script, according to the chart below. For any value that is not in the chart, the rectangle should be black.

Select Case Command

This command executes one chosen case among several instructions groups. The syntax is:

Select Case
    Case
       
    Case
       
End Select

Examples:

Select Case Engines
Case 0
    Text=”Engines off”
Case 1
    Text=”Engine 1 on”
Case 2
    Text=”Engine 2 on”
Case 3
    Text=”Engines 1 and 2 on”
Case else
    Text=”Status Error. Verify the engines”
End select

Exercises:

4. Insert two screens in your application.
5. Create a menu with the name of all the screens, using SelectMenu method from the E3 Viewer.
6. By clicking on screen’s name on the menu, open the selected screen.

Attachments:

Lesson3.zip