Operator Delete Statement

Operator to destroy data and free memory allocated with the 
Operator New Expression

Usage
   Delete buf
      or
   Delete[] buf

Parameters
   buf 
      A pointer to memory that has been allocated by New Expression 
      operator or New[] Expression operator, the array-version of 
      New Expression operator (a typed pointer must be provided in 
      accordance to the data type to delete).

Description
   The Delete Statement operator is used to destroy and free the memory of 
   an object created with New Expression operator. When deleting a TYPE, 
   its destructor will be called. Delete Statement operator should only be 
   used with addresses returned from New Expression operator.

   The array version of Delete Statement operator, Delete[] Statement 
   operator, is used to destroy an array of objects previously created with 
   New[] Expression operator, the array-version of New Expression operator. 
   Destructors will be called here as well.

   Delete Statement operator must be used with addresses returned from 
   New Expression operator, and Delete[] Statement operator with New[] 
   Expression operator, the array-version of New Expression operator. You 
   cannot mix and match the different versions of the operators.

   After the memory is deleted, the buf pointer will be pointing at invalid 
   memory. Calling Delete Expression twice on the same pointer value leads 
   to undefined behavior. It may be a good idea to set the buf pointer to 
   null (0), in order to guard against later code using it accidentally, 
   since null pointer dereferences are easier to find and debug.

   Calling Delete Statement operator on a null pointer induces no action.

   The memory deallocation process part provided by the Delete Statement 
   operator can be overloaded for user-defined types as a member operator 
   Delete Overload. The previous process part for data destruction can 
   never be modified.

   Note: Any operator Delete[] (Statement or Overload) and the only 
   Overload operator Delete are not compatible with sub-type polymorphism, 
   even using Override Virtual Destructor that may in addition induce 
   crashing.
   Instead of having to call such an operator Delete([]) Statement on 
   derived-type pointer, the safest way is to simply call (on base-type 
   pointer) an overridden user Virtual member procedure that will 
   automatically launch the operator Delete([]) Statement at derived-type 
   level.

Example
   Type Rational
      As Integer numerator, denominator
   End Type

   ' Create and initialize a Rational, and store its address.
   Dim p As Rational Ptr = New Rational(3, 4)

   Print p->numerator & "/" & p->denominator

   ' Destroy the rational and give its memory back to the system. 
   Delete p

   ' Set the pointer to null to guard against future accesses
   p = 0

   ' Allocate memory for 100 integers, store the address of the first one.
   Dim p As Integer Ptr = New Integer[100]

   ' Assign some values to the integers in the array.
   For i As Integer = 0 To 99
      p[i] = i
   Next

   ' Free the entire integer array.
   Delete[] p

   ' Set the pointer to null to guard against future accesses
   p = 0

Dialect Differences
   * Only available in the -lang fb dialect.

Differences from QB
   * New to FreeBASIC

See also
   * New Expression
   * Delete Overload
   * Deallocate

