Thread: Arrays, Structs, Pointers, and unexpected crashes

(GAH. Why? Why did it all have to disappear??? sorry for my frustration. After typing out my problem for about half an hour I was required to log back in, losing all of my work.)

Hello all again,

Because I don't want to type everything I said again, I'll just shorten it.

I have an array of a struct (named CAR). this array is named "cars" (its inside a struct named park)

Code:

typedef struct park
{
	CAR cars[NUM_CARS];
} Park;

I could do this to set a variable in one of the cars:

Code:

p->cars[i].variable=something; // This would work

But I needed a second array named dock. This array should have a link to certain CARs in the "cars" array. I tried this code.

Code:

p->cars[i].variable=something;
p->dock[j]=p->cars[i];
p->cars[i].variable=something_different;  // I want this to also affect p->dock[j]

unfortunately, changing something in "cars" didn't change the same CAR in "dock." When I set one equal to the other, it copied instead of making a link.

I realized my mistake and needed to have an array of pointers instead of an array of CARs. My new code:

Code:

typedef struct park
{
	CAR* cars[NUM_CARS];
	CAR* dock[NUM_CARS];
} Park;

now I can copy cars correctly (by copying their address), but I can no longer set variables:

Code:

p->dock[i]=p->cars[i];  // this now works.
p->dock[i].variable = something;  // this gives me a syntax error
p->dock[i]->variable = something;  // this crashes the program upon executing

So what did I do wrong and how do I fix it?

Thanks for listening,
Kairos

P.S. I kinda wrote this in a hurry and not as well since everything died. If this doesn't make sense please tell me and I will clear it up for you.

Wow. Thanks so much. Fast post too. I feel stupid for not catching that. I kinda facepalmed when you said that...

Well you saved me a night of pulling my hair out. Thanks again. Now my program will work flawlessly (I hope).

Thanks,
Kairos