I am creating a linked list program in C and I keep on getting a segmentation fault. I've narrowed the problem down to a few lines of code and I believe it has to do with checking for NULL. How can I fix this? Here's the code:
typedef struct node
{
int contents;
struct node *nextNode;
} Node;
deleteNode(Node *currentNode)
{
while((currentNode->contents) != NULL)
{
//.....Do Stuff.....
currentNode = currentNode->nextNode;
}
}
Thanks
Try checking to make sure that currentNode isn't NULL at the start of deleteNode(). I.e.
deleteNode(Node *currentNode)
{
if (currentNode == NULL) return;
// ...
// ...
}
If the problem is as I suspect, currentNode is a null pointer. Just ensure that currentNode is not null before you attempt to access it.
deleteNode(Node* currentNode)
{
while ((currentNode != NULL) && (currentNode->contents != NULL))
{
/* ... */
currentNode = currentNode->nextNode;
}
}
Well, I'm suspicious that this line:
while((currentNode->contents) != NULL)
is comparing the contents field of your Node structure, which is an int, with NULL... I would guess that this was supposed to be checking currentNode->nextNodeinstead!
So, probably: none of your contents are zero, so this test is true for every item in the list. Then the last item has a NULL currentNode->nextNode, which is assigned to currentNode, and it blows up dereferencing it the next time round the loop.
what happens when currentNode is NULL?. It is dereferencing a NULL memory in the while condition.
