Question

I wanted to create a generic Linked List in C. Following is the structure of the node:

typedef struct node {
    void *value;
    int size;        // n bytes
    ind index;       // index of the node
    struct node *next;
} Node;

And my delete_node function is as following. The search function sends a pointer to the Node I want to delete.

Node *search_list(Node *list, void *data, int n_bytes);
int delete_node(Node *list, Node *to_be_deleted);       // returns 1 on success

Inside the delete_node function I want to free up the memory pointed by void *value and then free up the memory allocated for the Node itself.

free(to_be_deleted->value);      // Would this work??
free(to_be_deleted);

Since it is void pointer we don’t know that how many bytes the object it is pointing to has occupied. How can we free up the memory for that?
Sorry if it is a stupid questions?

Answer 1

free(to_be_deleted->value);      // Would this work??

Straight forward answer , Yes this will work.

simple thing :

see the definitions of free() and malloc()

void free(void *) // free takes void* as argument so it will work

void* malloc(sizeof(type))

In mallocwe have to pass thesize that how many bytes we want to allocate.

but in free just pass the pointer and whatever bytes allocated to that pointer on heap storage it will be freed