Problem Statement

Dynamically allocated objects take their memory from a heap. The memory for an object is provided by an allocator which maintains the storage pool used for the heap. Often a call to allocator is denoted as where   T   is the type of an allocated object,   and   P   is a reference to the object. The storage pool chosen by the allocator can be determined by either:

In the former case objects can be allocated only in one storage pool. In the latter case objects of the type can be allocated in any storage pool or on the stack.

The task is to show how allocators and user-defined storage pools are supported by the language. In particular:

Explain what controls the storage pool choice in the language.

Let's start with the solution:

      SUBROUTINE CHECK(A,N)	!Inspect matrix A.
       REAL A(:,:)	!The matrix, whatever size it is.
       INTEGER N	!The order.
       REAL B(N,N)	!A scratchpad, size known on entry..
       INTEGER, ALLOCATABLE::TROUBLE(:)	!But for this, I'll decide later.
       INTEGER M

        M = COUNT(A(1:N,1:N).LE.0)	!Some maximum number of troublemakers.

        ALLOCATE (TROUBLE(1:M**3))	!Just enough.

        DEALLOCATE(TROUBLE)		!Not necessary.
      END SUBROUTINE CHECK		!As TROUBLE is declared within CHECK.