An allocation function shall be a class member function or a global
function; a program is ill-formed if an allocation function is declared
in a namespace scope other than global scope or declared static in
An allocation function attempts to allocate the requested amount of
If it is successful, it returns the address of the start
of a block of storage whose length in bytes is at least as large
as the requested size.
contiguity, and initial value of storage allocated by successive calls
to an allocation function are unspecified.
Even if the size of the space
requested is zero, the request can fail.
If the request succeeds, the
value returned by a replaceable allocation function
is a non-null pointer value ([basic.compound])
p0 different from any previously returned value p1,
unless that value p1 was subsequently passed to a
replaceable deallocation function.
Furthermore, for the library allocation functions
in [new.delete.single] and [new.delete.array],
p0 represents the address of a block of storage disjoint from the storage
for any other object accessible to the caller.
The effect of indirecting through a pointer
returned from a request for zero size is undefined.32
For an allocation function other than
a reserved placement allocation function ([new.delete.placement]),
the pointer returned on a successful call
shall represent the address of storage that is aligned as follows:
A program-supplied allocation function can obtain the address of the
currently installed new_handler using the
std::get_new_handler function ([get.new.handler]).
— end note
An allocation function that has a non-throwing
exception specification ([except.spec])
indicates failure by returning
a null pointer value.
Any other allocation function
never returns a null pointer value and
indicates failure only by throwing an exception ([except.throw]) of a type
that would match a handler ([except.handle]) of type
A global allocation function is only called as the result of a new
expression, or called directly using the function call
syntax, or called indirectly to allocate storage for
a coroutine state ([dcl.fct.def.coroutine]),
or called indirectly through calls to the
functions in the C++ standard library.