creating a pointer to an array of pointers?

crashmonkey · 09-09-2011, 04:42 PM

I have a class that contains a c array of pointers declared as...

Code:

struct blah  *array[15];

I need to create a pointer in another class that references the array such that i can search the array and change the data its pointers reference from within the other class.
I have tried declaring the pointer as

Code:

struct blah *pointer;

and even as a pointer to a pointer...

Code:

struct blah **pointer;

but I can't seem to access the array data properly. I just get crashes and BAD ACCESS errors.

I am assigning the pointer in a viewController viewDidLoad method.
The viewController contains both classes as ivars.
I'm not sure I am performing the assignment correctly, which may be the problem.

Code:

class2.pointer = [class1 getArray];

The getter method in class1 looks like this..

Code:

- struct blah *getArray{
     return array[0];
}

When I try to access the array from the class2 pointer I am doing this...

Code:

struct blah *new = pointer+index;
         if (new != NULL)
                do something;

This seems like it should be pretty straightforward , but I am not referencing or dereferencing the pointers correctly.
I'm thinking I am trying to get a pointer to point to the beginning address of the array that holds the pointers to other memory. I would then randomly access any of the array pointers using pointer math on the class2 pointer.
I don't know the proper syntax.

crashmonkey · 09-09-2011, 05:18 PM

Awesome! I figured it out.

It was just a simple matter of syntax.

Using a pointer to a pointer was correct

Code:

struct blah **pointer;

Then in the getter method I get the address of the first element of the array...

Code:

- (struct blah **)getArray{
     &return array[0];
}

Then when accessing the array with the pointer I needed parenthesis around the pointer expression..

Code:

struct blah *new = *(pointer+index);
         if (new != NULL)
                do something;

That works. A pointer to an array of pointers.