Encyclopedia > NUL

  Article Content

Null

Redirected from NUL

Null is a term used, often in computer science, to signify nothingness.

In computer programming, null is a special value for a pointer (or reference) that is used to signify that the pointer's target is not a valid data element. Often, 0 (zero) is used as the null value, as most operating systems consider it an error to try to access such a low memory address. Null is used in many other disciplines, and is not just used for pointers in programming. (Example: /dev/null, a virtual device[?] on UNIX systems)

The ASCII character code with code value 0 is called a null character, sometimes denoted as NUL.

In some languages, such as LISP, the designation is called nil.

In many disciplines, the concept of null allows a three-valued logic, with null indicating 'unknown'.

Note that this is not the same as the definition of nothing because it is more related to computer science.

See also: null set.



All Wikipedia text is available under the terms of the GNU Free Documentation License

 
  Search Encyclopedia

Search over one million articles, find something about almost anything!
 
 
  
  Featured Article
Roswell, New Mexico

... - FBI electronic reading room site on Roswell Geography Roswell is located at 33°23'14" North, 104°31'41" West (33.387160, ...