Language Reference

INTENT

Purpose

The INTENT attribute specifies the intended use of dummy arguments.

Format

>>-INTENT--(--+-IN----+---)--+----+--dummy_arg_name_list------->< +-OUT---+ '-::-' '-INOUT-'

dummy_arg_name

is the name of a dummy argument, which cannot be a dummy procedure or a dummy pointer

Rules

The INTENT attribute can take three forms:

• INTENT(IN) specifies that the dummy argument must not be redefined or become undefined during the execution of the subprogram.

• INTENT(OUT) specifies that the dummy argument must be defined before it is referenced within the subprogram. Such a dummy argument might not become undefined on invocation of the subprogram.

• INTENT(INOUT) specifies that the dummy argument can both receive and return data to the invoking subprogram.

An actual argument that becomes associated with a dummy argument with an intent of OUT or INOUT must be definable. Hence, a dummy argument with an intent of IN, or an actual argument that is a constant, a subobject of a constant, or an expression, cannot be passed as an actual argument to a subprogram expecting an argument with an intent of OUT or INOUT.

An actual argument that is an array section with a vector subscript cannot be associated with a dummy array that is defined or redefined (that is, with an intent of OUT or INOUT).

A dummy argument with an intent of IN cannot be used as an actual argument for the LOC intrinsic function.

The %VAL built-in function, used for interlanguage calls, can only be used for an actual argument that corresponds to a dummy argument with an intent of IN, or that has no intent specified. This constraint does not apply to the %REF built-in function.

Attributes Compatible with the INTENT Attribute
DIMENSION OPTIONAL TARGET VOLATILE

Examples

      PROGRAM MAIN
        DATA R,S /12.34,56.78/
        CALL SUB(R+S,R,S)
      END PROGRAM
 
      SUBROUTINE SUB (A,B,C)
        INTENT(IN) A
        INTENT(OUT) B
        INTENT(INOUT) C
        C=C+A+ABS(A)            ! Valid references to A and C
                                ! Valid redefinition of C
        B=C**2                  ! Valid redefinition of B
      END SUBROUTINE

Related Information

• Intent of Dummy Arguments
• Argument Association
• %VAL and %REF, for details on interlanguage calls
• Dummy Arguments