Databases
StackOverflow2013
Postsdbo
POWhy is there no "NULL reference" in C++?
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POWhy is there no "NULL reference" in C++?
    primarykey
    data
    text
    <p>I was reading the C++ FAQ - "<a href="http://www.parashift.com/c++-faq-lite/refs-vs-ptrs.html" rel="nofollow noreferrer">8.6 - When should I use references, and when should I use pointers?</a>" and in particular this statement:</p> <blockquote> <p>Use references when you can, and pointers when you have to.</p> <p>...</p> <p>The exception to the above is where a function's parameter or return value needs a "sentinel" reference — a reference that does not refer to an object. This is usually best done by returning/taking a pointer, and giving the NULL pointer this special significance (references must always alias objects, not a dereferenced NULL pointer).</p> </blockquote> <p>From what I've seen, the need for a "sentinel" reference is indeed often the reason to use pointers instead of references. What I'm wondering is: why doesn't C++ have a special "NULL value" for references? It seems it would make pointers almost unnecessary, which would solve many problems.</p> <p>So why wasn't it part of the language specification?</p> <p><strong>Edit:</strong></p> <p>I'm not sure my question is clear - I guess I'm not asking litterally about NULL references. Most often I read that in C++ "the reference is the object". And, in most OOP languages, objects can be NULL - Pascal, C#, Java, JavaScript, PHP, etc. in all these you can do <code>someObject = null</code> or <code>someObject := nil</code>. In fact, Pascal also supports pointers but still allows objects to be <code>nil</code>, since it has its use. So why is C++ somehow special and doesn't have a NULL object? Was it just an overlook or an actual decision?</p>
    singulars
    1. PO
      singulars
      1. PTAnswer
    1. This table or related slice is empty.
    1. PTQuestion
    1. USthis.lau_
    1. USthis.lau_
    plurals
    1. PL
      singulars
      1. LTLinked
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    2. PO
      singulars
      1. PTAnswer
    3. PO
      singulars
      1. PTAnswer
    1. VO
      singulars
      1. POWhy is there no "NULL reference" in C++?
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. POWhy is there no "NULL reference" in C++?
      1. This table or related slice is empty.
      1. VTUpMod
    1. COPray tell how that would remove the need for pointers?
      singulars
      1. POWhy is there no "NULL reference" in C++?
      1. USNathan White
    2. CO@nathanwhite Because then references would be syntactic sugar for pointers, presumably, that could be used whenever pointers are. Which, IMO, would completely remove some of the benefits of references.
      singulars
      1. POWhy is there no "NULL reference" in C++?
      1. UShvd
    3. CORead [Why does C++ have both pointers and references?](http://www2.research.att.com/~bs/bs_faq2.html#pointers-and-references) and [C++: null reference](http://stackoverflow.com/questions/4364536/c-null-reference).
      singulars
      1. POWhy is there no "NULL reference" in C++?
      1. USJesse Good
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload