macro
<cstddef> <cstdlib> <cstring> <cwchar> <ctime> <clocale> <cstdio>
NULL
Null pointer
This macro expands to a null pointer constant.
A null-pointer constant is an integral constant expression that evaluates to zero (like 0 or 0L), or the cast of such value to type void* (like (void*)0).
A null-pointer constant is an integral constant expression that evaluates to zero (such as 0 or 0L).
A
null-pointer constant is either an integral constant expression that evaluates to zero (such as
0 or
0L), or a value of type
nullptr_t (such as
nullptr).
A null pointer constant can be converted to any pointer type (or pointer-to-member type), which acquires a null pointer value. This is a special value that indicates that the pointer is not pointing to any object.