How much memory is my logical array using?

47

The situation with the current standard as well as the next revision is indeed inadequate in that the standard does not allow the practitioner to perform a suitable inquiry into the options supported by the processor. Thus the practitioner is left to do that separately a priori and then proceed with the program.

   use, intrinsic :: iso_fortran_env, only : lk => logical_kinds
   block
      print *, "Supported logical_kinds: ", lk
   end block
   block
      integer, parameter :: lk1 = lk(1), lk2 = lk(2), lk3 = lk(3), lk4 = lk(4)
      print *, "storage size lk1: ", storage_size(.true._lk1)
      print *, "storage size lk2: ", storage_size(.true._lk2)
      print *, "storage size lk3: ", storage_size(.true._lk3)
      print *, "storage size lk4: ", storage_size(.true._lk4)
   end block
end

C:\temp>gfortran p.f90 -o p.exe

C:\temp>p.exe
 Supported logical_kinds:            1           2           4           8          16
 storage size lk1:            8
 storage size lk2:           16
 storage size lk3:           32
 storage size lk4:           64