CODEWITHSUNDEEP
cpointerslinked-listmallocfree
Matt
Matt

Reputation: 1839

Memory Allocation Freeing

I'm currently writing a linked list and trying to free up memory allocations when I delete a node. However, after hours of trying to do this, I can't seem to get a clean valgrind output. 

void * pop(struct List *list)
{
    if(list->head == 0){
        return 0;
    }

    struct Node * tempNode = list->head->next;                                                                                                            
    free(list->head);
    list->head = tempNode;
    ...
}

I'm allocating the space by saying:

addNode(struct List *list, void *element){
    struct Node *node;
    node = (struct Node *)malloc(sizeof(node));
    ....
}

Basically in the pop function I want to take out the head of the list and make the head's next node the new head. I want to deallocate the memory that was given to head.

Thanks for any help

Upvotes: 1

Views: 156

Answers (3)

Sinan Ünür
Sinan Ünür

Reputation: 118118

node = malloc(sizeof(*node));

Allocate space for the thing pointed to by node.

Don't cast the return value of malloc. Doing so can mask the failure to #include <stdlib.h>.

Upvotes: 1

Yantao Xie
Yantao Xie

Reputation: 12896

It seems correct. Or are there some leaks in the other places? Or do you free the element itself as the parameter passed in ?

Upvotes: 0

Mysticial
Mysticial

Reputation: 471209

Woah, your malloc isn't correct. You have:

(struct Node *)malloc(sizeof(node));

What you need is:

(struct Node *)malloc(sizeof(struct Node));

In your original code, you are only allocating enough for a pointer. But you are trying allocate a Node object.

Upvotes: 3

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