'NULL' undeclared?

[Incinerator]

hey, I'm getting an error that says

'NULL' undeclared (first use this function)

and thats my last error to fix and I was just wondering how to go about it, since I have no idea what is wrong.

Thanks

 

[calhoun]

Whats Wrong? Its not defined.


Without some more details like Language or a Code Example we might be able to help.

 

[bobbydole]

right on!

in java null is usually in lowercase


if(Incinerator == null){
Incinerator= new Incinerator();
}

 

[Incinerator]

ok well this is in C++ and I'm trying to implement priority queues and it just keeps giving me that error, and only that error and its getting pretty annoying.

struct Cell
{
  Cell* next;
  int item;
  double priority;
  Cell(int i, Cell* n)
  {
    item = i;
    next = n;
  }
  Cell(Cell* L, int v, double p)
  {
    priority = p;
    item = v;
    next = L;
  }
};

struct pQueue
{
  Cell* ptr;
  pQueue()
  {
    ptr = null;
  }
};

I dont see whats wrong, with saying ptr = null...

 

[BillLeeLee]

In C++, it's NULL. All caps.

 

[Xipher]

Try capitalizing NULL

 

[movax]

Yeah, C++ only accepts NULL...you got it right in your thread title?

 

[tim_m]

i'm not sure if it's pre-defined in c++ but in c you need to include something from the standard library to get NULL, i.e.
#include <stdio.h>
so you may have to include something before it's defined, not sure though.

 

[nameless_centurian]

#define, baby!

 

[Xipher]

yea, thats another way to do it

#ifndef NULL
#define NULL 0L
#endif

think I got it right