ALLOCATED — Status of an allocatable entityALLOCATED(ARRAY) and ALLOCATED(SCALAR) check the allocation
status of ARRAY and SCALAR, respectively.
     SCALAR= keyword and allocatable
scalar entities are available in Fortran 2003 and later.
     RESULT = ALLOCATED(ARRAY)
 | 
RESULT = ALLOCATED(SCALAR)
      | 
| ARRAY | The argument shall be an ALLOCATABLE array. 
 | 
| SCALAR | The argument shall be an ALLOCATABLE scalar.
      | 
LOGICAL with the default logical
kind type parameter.  If the argument is allocated, then the result is
.TRUE.; otherwise, it returns .FALSE.
               program test_allocated
            integer :: i = 4
            real(4), allocatable :: x(:)
            if (.not. allocated(x)) allocate(x(i))
          end program test_allocated