In computing, a null pointer or null reference is a value saved for indicating that the pointer or reference does not refer to a valid object. Programs...

representation. Null device, a virtual file that discards data written to it, on Unix systems /dev/null Null pointer or reference (sometimes written NULL, nil,...

often occur because of errors in pointer use, particularly in C dynamic memory allocation. Dereferencing a null pointer, which results in undefined behavior...

pointer be explicitly initialized to the null pointer value, which is traditionally specified in C with the standardized macro NULL: int *ptr = NULL;...

system is able to detect run-time references to null pointers, a solution to the above is to assign 0 (null) to dp immediately before the inner block is...

unusable. This means that, for example, a pointer to 0 is never a valid pointer and can be used as a special null pointer value. Unlike the previously mentioned...

implemented as null-terminated character arrays. Low-level access to computer memory is possible by converting machine addresses to pointers. Procedures...

abbreviated as NUL (or NULL, though in some contexts that term is used for the null pointer). In 8-bit codes, it is known as a null byte. The original meaning...

following limits on programs: NULL checks are inserted to prevent segmentation faults Pointer arithmetic is limited Pointers must be initialized before use...

pointers that can be NULL require the user to check the pointer before using it and require specific code to handle the case when the object pointer is...

not be null. Rust instead uses Option for this purpose: Some(T) indicates that a value is present, and None is analogous to the null pointer. Option...

expression for rejecting all available candidates None, the keyword for the null pointer in Python Nones (disambiguation) Nothing (disambiguation) Zero (disambiguation)...

no appropriate object available. A null reference is impossible in standard-conforming C++. A null Animal* pointer is possible, and could be useful as...

confuse == with =. The advantage of avoiding null behavior can also be considered a disadvantage, as null pointer errors can be hidden and only appear much...

never again be used, no code will try to access the null pointer, and because the pointer is null, its memory is not deleted when it goes out of scope...

control access to a function. It is commonly seen when checking for null pointers or handling callbacks. Two examples of the term are related to a particular...

Windows actually make the zero page inaccessible to trap uses of null pointers. Such pointer values may legitimately indicate uninitialized values or sentinel...

termination of the code that made the invalid reference. A null pointer is usually represented as a pointer to address 0 in the address space; many operating systems...

null pointer to his design of the ALGOL W language and called it a "mistake": I call it my billion-dollar mistake. It was the invention of the null reference...

result of applying the unary * operator on a null pointer. Whether an exception is thrown for other null reference arguments is implementation-dependent...

done with moves (and confusingly sets the copied-from auto_ptr to a NULL pointer). These copy semantics mean that it cannot be used in STL containers...

can automatically detect such an invalid access (e.g. for the null value: a null pointer dereference error). This supports in analyzing the actual reason...

are still in use. If methods for a non-existent object are called, a null pointer exception is thrown. One of the ideas behind Java's automatic memory...

singly linked list. The first one uses the sentinel value NULL, and the second one a (pointer to the) sentinel node Sentinel, as the end-of-list indicator...

offsetof(st, m) \ ((size_t)&(((st *)0)->m)) This can be understood as taking a null pointer of type structure st, and then obtaining the address of member m within...

bugs; Swift has features addressing some common programming errors like null pointer dereferencing and provides syntactic sugar to help avoid the pyramid...

might return a null pointer and it is good programming practice to check for this: int *array = malloc(10 * sizeof(int)); if (array == NULL) { fprintf(stderr...

null_pointer at SourceForge (9 June 2011). "srm main.c" (C Source). srm 1.2.11, main.c CVS 1.16. SourceForge.net. Retrieved 7 January 2014. doj, null_pointer...

instance, creating a pointer with a null value and then attempting to use it is perfectly acceptable in C, leading to null-pointer errors. In contrast...

= NULL; // initialize invalid links to nil. if (head == NULL) { head = temp; // If the linked list is empty (i.e., the head node pointer is a null pointer)...