How to fix errors relating to pointers in C?

[Shane Fitz]

I am getting a warning and a common error in my code, and I need help understanding them.

The warning is:[Warning] assignment makes pointer from integer without a cast

Here is the code that i get the warning from:

line1 = biset_new(MAX_STRING); 
	line2 = bitset_new(MAX_STRING);
	bitset_un = bitset_new(MAX_STRING);
	bitset_in = bitset_new(MAX_STRING);

the left hand of the equals are all pointers to my bitset structure. The right hand side is a function i have written that returns a pointer to a bitset. MAX_STRING is defined as 256.


The error Im getting is: dereferencing pointer to incomplete type

And i get this error when i try to do something like:

bitset_un->size

Where 'size' is an int varible in the bitset struct. I want to access the size and items in my bitset. How can I do this? My bitset code is included below.

struct bitset{
	int size; 
	unsigned items[size];
};

[Oralloy]

This looks like you are using C, so I will answer in that vein. If you are using C++, there are already templates to handle bitsets.

The second definition in your bitset structure is not a legal array definition.

All array definitions must have a size that is computable at compile time.

Unless you want to play games with structure allocation, the "correct" definition of your bitset structure is probably more like this:

struct bitset{ 
    int size;  
    unsigned *items; 
};

And the "constructo r" will be something like this (you should provide appropriate error control, I've simply demonstrated one option using the assert macro):

struct bitset *bitset_new(int size)
{
  struct bitset *bitset;
  unsigned      *items;

  assert(0 <= size);

  bitset = (struct bitset *)malloc(sizeof struct bitset);
  items  = (unsigned *)malloc((sizeof unsigned) * size);

  assert(NULL != bitset);
  assert(NULL != items);

  bitset->items = items;

  return bitset;
}

Hopefully this helps some.

Good luck!

[donbock]

Oralloy: only one thing more is needed. Insert this line in the vicinity of your line 14:

bitset->size = size;

[Oralloy]

Thanks Don!