Open Watcom FORTRAN 77 Language Reference

Language Reference
Example:
DIMENSION A(10)
CALL SAM( A(3) )
END
SUBROUTINE SAM( B )
DIMENSION B(5)
.
.
.
END
In the previous example, array A is an actual argument and the array B is the dummy argument. Suppose
we wanted to know which element of A is associated with the 4th element of B. Then asv would have
value 3 since the array element A(3) is the actual argument, and dsv is 4. Then the 4th element in B is 3 +
4 - 1 = 6th element of A.
If the actual argument is a character array name, character array element name or character array element
substring which begins at character storage unit ach, then the character storage unit dch of the dummy
argument array is associated with the character storage unit ach + dch - 1 of the actual array. The size of
the dummy character array must not exceed the size of the actual argument array.
12.8.3.4 Procedures as Dummy Arguments
A dummy argument that is a dummy procedure can only be associated with an actual argument that is one
of the following.
1. Intrinsic function.
2. External function.
3. External Subroutine.
4. Another dummy procedure.
If the dummy argument is used as a subroutine (that is it is invoked using a CALL statement) then the
corresponding actual argument must either be a subroutine or a dummy procedure. If the dummy argument
is used as an external function, then the corresponding actual argument must be an intrinsic function,
external function or dummy procedure. Note that it may not be possible to determine in a given program
unit whether a dummy procedure is associated with a function or subroutine. In the following example it is
not possible to tell by looking at this program unit whether PROC is an external subroutine or function.
Example:
SUBROUTINE SAM( PROC )
EXTERNAL PROC
.
.
CALL SAM1( PROC )
.
.
.
END
280 Subprogram Arguments