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Since C23, a null pointer is represented with nullptr which is of type nullptr_t (something originally introduced to C++11), providing a type safe null pointer. [6] The C standard does not say that the null pointer is the same as the pointer to memory address 0, though that may be the case in practice.
A null pointer has a value reserved for indicating that the pointer does not refer to a valid object. Null pointers are routinely used to represent conditions such as the end of a list of unknown length or the failure to perform some action; this use of null pointers can be compared to nullable types and to the Nothing value in an option type.
The null object pattern solves this problem by providing a special NullAnimal class which can be instantiated bound to an Animal pointer or reference. The special null class must be created for each class hierarchy that is to have a null object, since a NullAnimal is of no use when what is needed is a null object with regard to some Widget base ...
It is often 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 of this character was like NOP —when sent to a printer or a terminal , it has no effect (some terminals, however, incorrectly display it as space ).
To expose dangling pointer errors, one common programming technique is to set pointers to the null pointer or to an invalid address once the storage they point to has been released. When the null pointer is dereferenced (in most languages) the program will immediately terminate—there is no potential for data corruption or unpredictable behavior.
A null pointer value explicitly points to no valid location. Dereferencing a null pointer value is undefined, often resulting in a segmentation fault. Null pointer values are useful for indicating special cases such as no "next" pointer in the final node of a linked list, or as an error
In C, variables with static storage duration that are not initialized explicitly are initialized to zero (or null, for pointers). [ 3 ] Not only are uninitialized variables a frequent cause of bugs, but this kind of bug is particularly serious because it may not be reproducible: for instance, a variable may remain uninitialized only in some ...
Null device, a virtual file that discards data written to it, on Unix systems /dev/null; Null pointer or reference (sometimes written NULL, nil, or None), an object pointer (or reference) not currently set to point (or refer) to a valid object