Thread: Chaining Hash Tables (in C)

Code:

struct foo {
    int bar;
};
...
struct foo *baz;
...
baz->bar = 10; /* segfault in the making */

Baz doesn't actually point to an allocated instance of 'struct foo', so you can't try to access 'bar'.


Quzah.

Originally Posted by vdk_au

hmmm...but that's not what i wrote....i think

It's called teaching. I was showing you that you can't access the members of a structure via a pointer, if your pointer doesn't actually point to anything. Now let's look back at my last post, to see if you can make the connection:

Originally Posted by quzah

Code:

for(i=0; i<20; i++)
{
   ov->array[i]->head = NULL;
   ov->array[i] = NULL;
}

"ov" has an array of poitnters. These pointers don't point at any actual instances, so you can't try to access "head". Doing so is why your program crashes.

There's another problem with this code, that you'd have, if you actually allocated space. It would be a memory leak. But, since you didn't actually allocate anything for your array of pointers to point at, you get a crash.


Quzah.