cppreference operator new, operator new[]

NOTE:

1、custom allocation operator overload new delete

2、原文对alignment进行了详细说明

Defined in header <new>

Function signature

replaceable allocation functions

replaceable non-throwing allocation functions

non-allocating placement allocation functions

user-defined placement allocation functions

class-specific allocation functions

class-specific placement allocation functions

1)

This function is required to return a pointer suitably aligned to point to an object of the requested size.

Return value

1-4) non-null pointer to suitably aligned memory of size at least size

5-8) non-null pointer to suitably aligned memory of size at least size, or null pointer on allocation failure

9-10) ptr

11-22) same as (1-4) if the function does not return on allocation failure, otherwise same as (5-8)