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# Standard library header <cstddef>

From cppreference.com
< cpp‎ | header

This header was originally in the C standard library as `<stddef.h>`.

This header is part of the utility library.

### [edit] Macros

NULL | implementation-defined null pointer constant (macro constant) [edit]
offsetof | byte offset from the beginning of a standard-layout type to specified member (function macro) [edit]

### [edit] Types

size_t | unsigned integer type returned by the `sizeof` operator (typedef) [edit]
ptrdiff_t | signed integer type returned when subtracting two pointers (typedef) [edit]
nullptr_t (C++11) | the type of the null pointer literal `nullptr` (typedef) [edit]
max_align_t (C++11) | POD type with alignment requirement as great as any other scalar type (typedef) [edit]

### [edit] Notes

- NULL is also defined in the following headers:
  - `<clocale>`
  - `<ctime>`
  - `<cstring>`
  - `<cstdio>`
  - `<cwchar>`
- std::size_t is also defined in the following headers:
  - `<ctime>`
  - `<cstring>`
  - `<cstdio>`
  - `<cwchar>`

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