CODEWITHSUNDEEP
fortran
user18371559
user18371559

Reputation: 67

Purpose of KIND= when declaring variables

After spending some time trying to understand how KIND works in Fortran I'm still in doubt. I would like to know if, e.g., INTEGER(KIND = c_intptr_t) is equivalent toINTEGER(c_intptr_t)?

If yes, which way is the preferred way?

Upvotes: 2

Views: 163

Answers (1)

francescalus
francescalus

Reputation: 32431

As a type declaration the two forms (for kind parameter k) integer (kind = k) and integer (k) are indeed equivalent.

This is true in type declaration statements

integer (kind=k) x
integer (k) y       ! x and y are integers with kind parameter k

and in other places

x = [integer(kind=k) :: 1, 2, 3]
y = [integer(k) :: 1, 2, 3]

The same holds for the intrinsic types real(kind=k), complex(kind=k) and logical(kind=k). One has to be careful with character:

character(kind = k) c  ! Length 1, kind k
character(k) d         ! Length k, default kind
character(l, k) e      ! Length l, kind k

Preferred form is subjective and you should follow your style guide consistently.

For derived types this is not necessarily the case:

type t(k)
  integer, kind :: k=58
end type t

type(t(kind=12)) :: x  ! Not valid: kind parameter is not "kind"
type(t(k=12)) :: y
type(t(12)) :: z

end

Upvotes: 3

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