[diff.null]

# Annex C (informative) Compatibility [[diff]](./#diff)

## C.8 C standard library [[diff.library]](diff.library#diff.null)

### C.8.3 Modifications to definitions [[diff.mods.to.definitions]](diff.mods.to.definitions#diff.null)

#### C.8.3.4 Macro NULL [diff.null]

[1](#1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/compatibility.tex#L3753)

The macroNULL,
defined in any of[<clocale>](clocale.syn#header:%3cclocale%3e "28.3.5.1 Header <clocale> synopsis [clocale.syn]"),[<cstddef>](cstddef.syn#header:%3ccstddef%3e "17.2.1 Header <cstddef> synopsis [cstddef.syn]"),[<cstdio>](cstdio.syn#header:%3ccstdio%3e "31.13.1 Header <cstdio> synopsis [cstdio.syn]"),[<cstdlib>](cstdlib.syn#header:%3ccstdlib%3e "17.2.2 Header <cstdlib> synopsis [cstdlib.syn]"),[<cstring>](cstring.syn#header:%3ccstring%3e "27.5.1 Header <cstring> synopsis [cstring.syn]"),[<ctime>](ctime.syn#header:%3cctime%3e "30.15 Header <ctime> synopsis [ctime.syn]"),
or [<cwchar>](cwchar.syn#header:%3ccwchar%3e "28.7.3 Header <cwchar> synopsis [cwchar.syn]"),
is an implementation-defined null pointer constant in
C++ ([[support.types]](support.types "17.2 Common definitions"))[.](#1.sentence-1)