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WTF??!! NULL is not defined in MSVC60??!!

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Started by exa_einstein August 04, 2004 08:15 AM

106 comments, last by null_pointer 19 years, 8 months ago

exa_einstein

122

Author

August 04, 2004 08:15 AM

I tried to compile a system of some nested classes and what happenned.. (small code dump:)



// in header file of the class

class gravityobjectsystem:public spaceobject
{
	spaceobject* soa;
	int nso;
public:
	gravityobjectsystem();
	virtual ~gravityobjectsystem();

///...........
// and then in .cpp file ...

gravityobjectsystem::gravityobjectsystem()  //constructor
{
	nso=0;
	soa=NULL;
}
//....

I thought that this sholdn't be a problem, but MSVC6.0 came with two errors: error C2065: 'NULL' : undeclared identifier //??????!!!!!! error C2440: '=' : cannot convert from 'int' to 'class spaceobject *' does somebody had any similar problem? I though NULL is valid zero pointer really EVERYWHERE? ISN'T??!! WTF?!!! helpme... (i don't want to #define my own NULL) exa_einstein

When I was younger, I used to solve problems with my AK-47. Times have changed. I must use something much more effective, killing, percise, pernicious, efficient, lethal and operative. C++ is my choice.

Namethatnobodyelsetook

1,260

August 04, 2004 08:19 AM

Just use 0 (zero). Seriously

exa_einstein

122

Author

August 04, 2004 08:27 AM

I know this, but question here is a little more about that "Has the NULL disappeared?" bug in visualC? (I have really checked everything)

ok,ok. now I use soa=(spaceobject*)0; because soa doesn't look like normal integer with it...

Agony

3,452

August 04, 2004 08:45 AM

NULL is #defined or whatnot in various library headers. If you don't include any of these in your project, then NULL is just an undeclared identifier. If you really want you can always add

#ifndef NULL#define NULL 0#endif

to your code, although switching to simply using 0 might be just as good. Only a few rare systems using something other than 0 for NULL. I'd switch, but I'm too lazy at the moment. Actually, if it's a big enough project, I'd probably just make my own const variable that matched the naming convention of the rest of my constants, and was in the proper namespace, too, if I was using namespaces.

"We should have a great fewer disputes in the world if words were taken for what they are, the signs of our ideas only, and not for things themselves." - John Locke

Enigma

1,410

August 04, 2004 08:55 AM

class Null{	public:		template <typename TYPE>		operator TYPE*() const		{			return 0;		}};const Null null;GravityObjectSystem::GravityObjectSystem(){	aDescriptiveName = 0;	anotherDescriptiveName = null;}

Simple, clean, unambiguous.

Enigma

Qw3r7yU10p!

819

August 04, 2004 08:58 AM

Quote:Original post by Enigma
*** Source Snippet Removed ***
Simple, clean, unambiguous.

Enigma

nice

evolutional

1,397

August 04, 2004 09:00 AM

Actually, you'll have to define your own NULL - because it's normal definition place is in the windows.h headers (or one hanging off that).

Enigma: Sweet [wink]

merlin9x9

174

August 04, 2004 09:06 AM

If I'm not mistaken, stddef.h always defines it. Of course, as Namethatnobodyelsetook mentioned, 0 is the correct C++ equivalent.

KulSeran

3,272

August 04, 2004 09:41 AM

Then why is there the line:

#define NULL ((void *)0)

in windows.h?

My Blog

vovansim

336

August 04, 2004 11:43 AM

Hi,

Quote:Original post by exa_einstein
I thought that this sholdn't be a problem, but MSVC6.0 came with two errors:

error C2065: 'NULL' : undeclared identifier //??????!!!!!!
error C2440: '=' : cannot convert from 'int' to 'class spaceobject *'

does somebody had any similar problem? I though NULL is valid zero pointer really EVERYWHERE? ISN'T??!! WTF?!!!

You thought wrong. NULL is *not* defined everywhere. One of these days, try to compile the following code:

int main() {  void* ptr = NULL;  return 0;}

I just did, and GCC gave me the following:

test.c: In function `main':test.c:2: `NULL' undeclared (first use in this function)test.c:2: (Each undeclared identifier is reported only oncetest.c:2: for each function it appears in.)

That is because NULL is not a symbol defined by default, but is contained in stdlib.h. (And also happens to be defined in windows.h, and some other headers.)

Vovan

Vovan

WTF??!! NULL is not defined in MSVC60??!!

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