On GoTo

Syntax

On Index Variable GoTo Label1 {,...Labeln }

Overview

Cause the program to jump to different locations based on a variable index.

Parameters

Index Variable is a constant, variable, or expression, that specifies the label to jump to. Label1...Labeln are valid labels that specify where to branch to.

Example

  Device = 24HJ128GP502           ' Select the device to compile for
  Declare Xtal = 16

  Dim Index as Byte

  Cls                           ' Clear the LCD
  Index = 2                     ' Assign Index a value of 2
Start:                            ' Jump to label 2 (Label_2) because Index = 2
  On Index GoTo Label_0, Label_1, Label_2

Label_0:
  Index = 2                     ' Index now equals 2
  Print At 1,1,"Label 0"         ' Display the Label name on the LCD
  DelayMs 500                    ' Wait 500ms
  GoTo Start                    ' Jump back to Start
Label_1:
  Index = 0                     ' Index now equals 0
  Print At 1,1,"Label 1"         ' Display the Label name on the LCD
  DelayMs 500                    ' Wait 500ms
  GoTo Start                    ' Jump back to Start
Label_2:
  Index = 1                     ' Index now equals 1
  Print At 1,1,"Label 2"         ' Display the Label name on the LCD
  DelayMs 500                    ' Wait 500ms
  GoTo Start                    ' Jump back to Start

The above example we first assign the index variable a value of 2, then we define our labels. Since the first position is considered 0 and the variable Index equals 2 the On GoTo command will cause the program to jump to the third label in the list, which is Label_2.

View original PDF page 316

Open page in PDF

Notes.

On GoTo is useful when you want to organise a structure such as: -

If Var1 = 0 Then GoTo Label_0  ' Var1 = 0: go to label "Label_0"
If Var1 = 1 Then GoTo Label_1  ' Var1 = 1: go to label "Label_1"
If Var1 = 2 Then GoTo Label_2  ' Var1 = 2: go to label "Label_2"

You can use On GoTo to organise this into a single statement: -

On Var1 GoTo Label_0, Label_1, Label_2

This works exactly the same as the above If...Then example. If the value is not in range (in this case if Var1 is greater than 2), On GoTo does nothing. The program continues with the next instruction.

See also : Branch, BranchL, On Gosub.

View original PDF page 317

Open page in PDF