 |
» |
|
|
|
Introduces a function subprogram. Syntax[RECURSIVE] [type-spec] FUNCTION |
function-name ([dummy-arg-name-list]) |
|
|
|
- RECURSIVE
is a keyword that must be specified in the FUNCTION
statement if the function is either directly or indirectly recursive.
The RECURSIVE
clause can appear at most once, either before or after type-spec.
It is not an error to specify RECURSIVE
for a nonrecursive function. A recursive function that calls itself directly must also
have the RESULT
clause specified (see below). - type-spec
is a valid type specification (INTEGER,
REAL, LOGICAL,
CHARACTER, TYPE
(name),
etc.). The type and type parameters of the function result can be
specified by type-spec or by declaring
the result variable within the function subprogram, but not by both.
The implicit typing rules apply if the function is not typed explicitly. If the function result is array-valued or a pointer, the appropriate
attributes for the result variable (which is function-name,
or result-name if specified) must be
specified within the function subprogram. - function-name
is the name of the function subprogram being defined. - dummy-arg-name-list
is a comma-separated list of dummy argument names
for the function. - result-name
is the result variable. If the RESULT
clause is not specified, function-name
becomes the result variable. If result-name
is given, it must differ from function-name,
and function-name must not then be declared
within the function subprogram. As noted above, a recursive function that calls itself directly
must have the RESULT
clause specified. For other functions, the RESULT
clause is optional.
DescriptionA FUNCTION
statement introduces an external, module, or internal function subprogram. ExamplesPROGRAM main
...
CONTAINS
! f is an internal function
FUNCTION f(x)
f = 2*x + 3
END FUNCTION f
! recursive function, which must specify RESULT clause
RECURSIVE INTEGER FUNCTION factorial (n) &
RESULT (factorial_value)
IMPLICIT INTEGER (a-z)
IF (n <= 0) THEN
factorial_value = 1
ELSE
factorial_value = n * factorial (n-1)
END IF
END FUNCTION factorial
END PROGRAM main |
Related statementsCONTAINS,
END, INTENT,
INTERFACE, OPTIONAL,
and the type declaration statements Related conceptsFor related information, see the following: |
Printable version
