struct arrays

This is just a basic question. I've created a struct that needs to create mutliple instances, but of a constantly changing number.

Grab number of objects from memory.

Code:

struct _NumOfObjects
{
	unsigned short Max;
	unsigned short Num;	
};
_NumOfObjects * NumOfObjects = ( _NumOfObjects * ) OTNumAddy;

Code:

struct _Lengths
{
	float AX;
    float TrueBX;
    float ExtremeBX;
	float AY;
    float TrueBY;
    float ExtremeBY;

    float dist; 
    float mx, my, mz;
} Length[NumOfObjects->Num];

I need to create an instance for each seperate object, but I get this error:

error C2057: expected constant expression
error C2466: cannot allocate an array of constant size 0

Is there a way to do this without a constant? The num of objects changes quite frequently.

Are you using C or C++? In C++, you'd use a vector and specify the size when you create it. In C you could use malloc to dynamically allocate the array, or maybe use variable length arrays.

BTW, technically you're not allowed to use any name that starts with an underscore followed by a capital letter.

I'm using C++ and I'm not very familiar with C functions =/

Originally Posted by silentkarma

Code:

_NumOfObjects * NumOfObjects = ( _NumOfObjects * ) OTNumAddy;

WTF?

>> I'm using C++
Ok, then:

Code:

std::vector<_Lengths> Length(NumOfObjects->Num);

You have to make sure NumOfObjects is valid at that point, so I'm not sure making it global is a good idea, but hopefully you just did that as an example (or because you thought it was necessary for a struct -- it's not).

I think the problem is (like robwhit said), this:

Code:

_NumOfObjects * NumOfObjects = ( _NumOfObjects * ) OTNumAddy;

What do you mean by it?

Originally Posted by g4j31a5

I think the problem is (like robwhit said), this:

Code:

_NumOfObjects * NumOfObjects = ( _NumOfObjects * ) OTNumAddy;

What do you mean by it?

This is assigning a static memory address to this struct. This is for a game. I hope this makes sense. I'm doing calculations on each object and decided to use struct arrays. I figured this would be the easiest way because I can easily iterate through objects.

What is OTNumAddy?

Originally Posted by Daved

What is OTNumAddy?

const unsigned long OTNumAddy = 0x4BB206E2;

So NumOfObjects->Num is the value found at 0x4BB206E4. Do you have any idea how the compiler should know what will be at this address when you execute the code?

--
Mats