Arrays can have the allocatable attribute:
! One dimensional allocatable array integer, dimension(:), allocatable :: foo ! Two dimensional allocatable array real, dimension(:,:), allocatable :: bar
This declares the variable but does not allocate any space for it.
! We can specify the bounds as usual allocate(foo(3:5)) ! It is an error to allocate an array twice ! so check it has not been allocated first if (.not. allocated(foo)) then allocate(bar(10, 2)) end if
Once a variable is no longer needed, it can be deallocated:
If for some reason an
allocate statement fails, the program will stop. This can be prevented if the status is checked via the
real, dimension(:), allocatable :: geese integer :: status allocate(geese(17), stat=status) if (stat /= 0) then print*, "Something went wrong trying to allocate 'geese'" stop 1 end if
deallocate statement has
stat keyword too:
deallocate (geese, stat=status)
status is an integer variable whose value is 0 if the allocation or deallocation was successful.