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Invokes a subroutine. SyntaxCALL subr-name[([ subr-act-arg-spec-list ])] |
- subr-name
is the name of the subroutine being invoked. - actual-argument-list
is a comma-separated list of entities of the form: [keyword =]actual-argument - actual-argument
is one of the following: - keyword
is one of the dummy
argument names of the subroutine being invoked. If any keyword is specified, the subroutine interface must be explicit.
DescriptionA CALL statement is used to invoke (call) a subroutine,
and to specify actual arguments, if any. Execution of the subroutine
begins with the first executable statement. The following sequence
of events occurs when a CALL statement executes: Actual arguments that are expressions are evaluated. The actual arguments are associated with the corresponding
dummy arguments. Control transfers to the subroutine being called,
and the subroutine executes. Control returns from the subroutine, normally to
the statement following the CALL statement, or to a statement label indicated by
an alternate return argument—*label or &label. (The & label form is provided as a compatibility extension and
can be used in fixed source form only.)
A subroutine can call itself, directly or indirectly; in this
case the keyword RECURSIVE must be specified in the SUBROUTINE statement of the subroutine definition. The %VAL and %REF built-in functions are provided as HP extensions.
They can be used to change argument-passing conventions calling
a routine written in another language. The only subroutine invocation other than by the CALL statement in Fortran 90 is through “defined
assignment”, where a defined type assignment operator that
has been defined by means of a subroutine is used. Examples! Interface for subroutine draw
INTERFACE
SUBROUTINE draw (x_start, y_start, x_end, y_end, form, scale)
REAL x_start, y_start, x_end, y_end
CHARACTER (LEN = 6), OPTIONAL :: form
REAL, OPTIONAL :: scale
END SUBROUTINE draw
END INTERFACE
! References to draw
! arguments given by position; optional argument scale omitted
CALL draw (5., -4., 2., .6, ”DASHED”)
! arguments given by keyword; optional argument form omitted
CALL draw (scale=.4, x_end=0., y_end=0., x_start=.5, y_start=.3) |
Related statementsINTERFACE and SUBROUTINE Related conceptsFor related information, see the following: |
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