In C#, if you want to indicate that an integer may or may not be there, you can mark it nullable, like this: int? x = null; This is useful when you don’t have a value that’s “invalid”, like 0, that lets you know the value isn’t there. In Fortran, marking a scalar allocatable achieves a similar res…

Yes, the language states that all allocatable variables and components have an initial status of unallocated.

You may find gfortran’s behavior surprising in this regard. You can bypass the surprise (allocated status upon second call) by explicitly deallocating the local allocatable objects before exiting the procedure.

[image] shahmoradi: You may find gfortran’s behavior surprising in this regard. Which behavior are you referring to? The following implicit none type :: my_type real, allocatable :: ent real, allocatable :: lvg end type call s(5) call s(6) contains subroutine s(n) integer, …

This is a relevant discussion: [image] Best practice: Deallocating allocatable arrays explicitly vs implicitly Help I would only remind you that you do not get the choice of implicit deallocation in procedures when compiling with gfortran using heap arrays (gfortran -fmax-…

I’ve come across the following question on StackOverflow, which may be related to the unexpected behavior of allocatable by Gfortran (linked in the above post, which is still reproducible with Gfortran-14 on Godbolt). Indeed, this may be a bug of the option -fmax-stack-var-size itself, though not su…

Can I guarantee `allocatable` variables to start out not allocated?

Help

shahmoradi November 22, 2024, 5:17pm 5

This is a relevant discussion:

Maybe the new gfortran has improved.

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Can I guarantee `allocatable` variables to start out not allocated?

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