Open Watcom FORTRAN 77 Language Reference

FORTRAN Statements
2.48 Assigned GO TO Statement
GO TO i [[,] (s [,s]...)]
where:
i
s
is an integer variable name.
is the statement label of an executable statement that appears in the same program unit as the
assigned GO TO statement.
The variable i must be defined with the value of a statement label of an executable statement that appears
in the same program unit (see the ASSIGN statement). The execution of the assigned GO TO statement
causes a transfer of control to the statement that is identified by that label.
Example:
INTEGER RET
X = 0.0
ASSIGN 100 TO RET
GO TO 3000
100 X = X + 1
ASSIGN 110 TO RET
GO TO 3000
110 X = X + 1
.
.
.
* Print both X and its square root
3000 Y = SQRT( X )
PRINT *, X, Y
GO TO RET
In the above example, we illustrate the use of the ASSIGN statement and the assigned GO TO statement to
implement a "local subroutine" in a program unit. A sequence of often-used code can be "called" using the
unconditional GO TO statement and "return" is accomplished using the assigned GO TO statement. Care
must be exercised to properly assign the return label value.
If a list of statement labels is present then the statement label assigned to i must be in the list. If it is not in
the list, an error will occur when the assigned GO TO statement is executed. Unlike the computed GO TO
statement, execution does not continue with the next statement. This is demonstrated by the following
example. Note that the "," preceding the statement label list is optional.
Example:
Assigned GO TO Statement 81