F
5.3.5 Delete [expr.delete]
1 The delete-expression operator destroys a most derived object (1.8) or array created by a new-expression.
delete-expression:
::opt delete cast-expression
cast-expression
The first alternative is for non-array objects, and the second is for arrays. The operand shall have a pointer
type, or a class type having a single conversion function (12.3.2) to a pointer type. The result has type
void.
2 If the operand has a class type, the operand is converted to a pointer type by calling the above-mentioned
conversion function, and the converted operand is used in place of the original operand for the remainder of
this section. In either alternative, if the value of the operand of delete is the null pointer the operation
has no effect. In the first alternative (delete object), the value of the operand of delete shall be a pointer
to a non-array object or a pointer to a sub-object (1.8) representing a base class of such an object (clause
10). If not, the behavior is undefined. In the second alternative (delete array), the value of the operand of
delete shall be the pointer value which resulted from a previous array new-expression.72) If not, the
behavior is undefined. [Note: this means that the syntax of the delete-expression must match the type of the
object allocated by new, not the syntax of the new-expression. ] [Note: a pointer to a const type can be
the operand of a delete-expression; it is not necessary to cast away the constness (5.2.11) of the pointer
expression before it is used as the operand of the delete-expression. ]
3 In the first alternative (delete object), if the static type of the operand is different from its dynamic type, the
static type shall be a base class of the operand’s dynamic type and the static type shall have a virtual
destructor or the behavior is undefined. In the second alternative (delete array) if the dynamic type of the
object to be deleted differs from its static type, the behavior is undefined.73)
4 The cast-expression in a delete-expression shall be evaluated exactly once. If the delete-expression calls
the implementation deallocation function (3.7.3.2), and if the operand of the delete expression is not the
null pointer constant, the deallocation function will deallocate the storage referenced by the pointer thus
rendering the pointer invalid. [Note: the value of a pointer that refers to deallocated storage is indeterminate.]
5 If the object being deleted has incomplete class type at the point of deletion and the complete class has a
non-trivial destructor or a deallocation function, the behavior is undefined.
6 The delete-expression will invoke the destructor (if any) for the object or the elements of the array being
deleted. In the case of an array, the elements will be destroyed in order of decreasing address (that is, in
reverse order of the completion of their constructor; see 12.6.2).
7 The delete-expression will call a deallocation function (3.7.3.2).
8 [Note: An implementation provides default definitions of the
global deallocation functions
operator delete() for non-arrays (18.4.1.1) and operator delete[]() for arrays (18.4.1.2).
A C + + program can provide alternative definitions of these functions (17.4.3.4), and/or class-specific versions
(12.5). ] When the keyword delete in a delete-expression is preceded by the unary :: operator, the
global deallocation function is used to deallocate the storage.
9 Access and ambiguity control are done for both the deallocation function and th destructor (12.4, 12.5).
