On...GoSub, On...GoTo Statements

Description

Branch to one of several specified lines, depending on the value of an expression.

Syntax

On expression GoSub destinationlist

On expression GoTo destinationlist

The On...GoSub and On...GoTo statement syntax has these parts:

Part	Description

expression	Any numeric expression that evaluates to a whole number between 0 and 255, inclusive. If expression is any number other than a whole number, it is rounded before it is evaluated.
destinationlist	List of line numbers or line labels separated by commas.

Remarks

The value of expression determines which line in destinationlist is branched to. If the value of expression is less than 1 or greater than the number of items in the list, one of the following results occurs:

If expression is:	Then

Equal to 0	Control drops to the statement following On...GoSub or On...GoTo.
Greater than number of items in list	Control drops to the statement following On...GoSub or On...GoTo.
Negative	An error occurs.
Greater than 255	An error occurs.

You can mix line numbers and line labels in the same list. There is no practical limit to the number of line labels and line numbers you can use with On...GoSub and On...GoTo. However, if you use more labels or numbers than will fit on a single line, you must use the line-continuation character to continue the logical line onto the next physical line.

Tip

Select Case provides a more structured and flexible way to perform multiple branching.

See Also

GoSub...Return Statement, GoTo Statement, Select Case Statement.

Example

This example uses the On...GoSub and On...GoTo statements to branch to subroutines and line labels respectively.

Sub OnGosubGotoDemo()
    Number = 2    ' Initialize variable.
    ' Branch to Sub2.
    On Number GoSub Sub1, Sub2    ' Execution resumes here after 
    ' On...GoSub.
    On Number GoTo Line1, Line2    ' Branch to Line2.
    ' Execution does not resume here after On...GoTo.
    Exit Sub
Sub1:
    MyString = "In Sub1" : Return
Sub2:
    MyString = "In Sub2" : Return
Line1: 
    MyString = "In Line1"
Line2: 
    MyString = "In Line2"
End Sub