GOTO

Transfer program control

WSupported on Windows
USupported on Unix
VSupported on OpenVMS
NSupported in Synergy .NET
 
GOTO label

or

GOTO(label[, ...]), selector

Arguments

label

A single statement label or a list of one or more statement labels that exist in the program. The first label is element 1, the second is element 2, and so forth.

selector

An expression whose value selects the corresponding element from the list of labels. (n)

Discussion

The GOTO statement transfers execution control to a specified label. The unconditional form of this statement specifies a single label. The computed form of this statement specifies a list of labels and a selection expression whose value indicates the desired label.

In the computed form of the GOTO statement, if selector is between 1 and the number of elements in label, the corresponding element is selected and control immediately transfers to the to the named label. However, if the value is less than 1 or more than the number of elements in label, no element is selected and execution continues with the statement following the GOTO.

Examples

This subroutine takes a result value to decide which code section to process. If the routine decide returns a result value of 1, control is transferred to lbl1. A value of 2, 3, or 4 transfers control to labels lbl2, lbl3, or lbl4, respectively. Any other value generates the message “… invalid ­result.”

subroutine choice
    a_data      ,a
record
    result      ,d2
proc
loop,
    xcall decide(a_data, result)
    goto (lbl1, lbl2, lbl3, lbl4), result
    writes(TTCHN, "... invalid result")
    goto loop
lbl1,
    writes(TTCHN, "Processing result #1")
    goto loop
lbl2,
    writes(TTCHN, "Processing result #2")
    goto loop
lbl3,
    writes(TTCHN, "Processing result #3")
    goto loop
lbl4,
    xreturn
endsubroutine
subroutine decide
    a_data      ,a
    result      ,d
proc
    display(TTCHN, "Result value? ")
    reads(TTCHN, %a(result))
    return
endsubroutine
Tip

We recommend that you not use GOTO when the logic can be written using structured statements instead. For example, we could rewrite the above code as follows:

subroutine choice
    a_data      ,a
external function
    decide      ,d
proc
    repeat
      begin
        using %decide select
          begincase
          (1),
            writes(TTCHN, "Processing result #1")
          (2),
            writes(TTCHN, "Processing result #2")
          (3),
            writes(TTCHN, "Processing result #3")
          (4),
            xreturn
writes(TTCHN, "... invalid result")
        endusing
      end
endsubroutine