c - Malloc of pointers in structs + pointer arithmetic + free() + linkedList

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I'm trying to implement a
linked-list data structure which each node has a identifier key, some data of variable
length (malloc), and a pointer to the next node. Now I want to have 3 functions which
respectively: sets a new node to the front of the list, prints the values of a given
node using identifier key, and deletes a given
node.

The struct I have for the node is as
follows:

struct node {

            char key[5];
 int* data;
 node* next;
};
struct
            node* headNode =
            NULL;

I
have questions regarding each of functions. I will list the function codes I have and
ask questions regarding that specific function
below:

The code for my set
function:

void command_set (char
            key[], int val[], int numOfVal){
 struct node* temp =
            (node*)malloc(sizeof(node));
 strcpy(temp->key, key);

            temp->data = (int*)malloc(numOfVal*sizeof(int));


            *(temp->data) = *(val);
 temp->next = entry_head;
 entry_head
            = temp;

            return;
}

Now
I have one question regarding this function:

1)
Is my method of storing the data valid? i.e. "temp->data =
(int*)malloc(numOfValuessizeof(int));" + "(temp->data) =
*(val);". What I'm trying to do is dynamically allocate some memory, then store the
given values as my node's data in that memory.

/>

The code for my print
function:

void printNode (char
            key[], int numOfVal){
 int i;
 struct node *currentNode =
            headNode;

 while(currentNode->next!=NULL){


            if(!strcmp(currentNode->key,key) ){
 for(i=0; i            i++){
 printf("%d ",*((currentNode->data)+i));
 }

            return;
 }
 currentNode =
            currentNode->next;
}

I
have a one question regarding this function:

2)
The data of a node is a list of integers, so does my way of printing out each integer
actually work? i.e. "*((currentNode->data)+i)". What I'm trying to do is by using
pointer arithmetic I print all the ints stored under data.

---

The code for
my delete function:

void
            deleteNode (char key[]){
 struct node *currentNode =
            headNode;

 struct node *prevNode = headNode;

            while(currentNode->next!=NULL){
 if(!strcmp(currentNode->key,key)
            ){
 prevNode->next = currentNode->next;

            free(currentNode->data);
 free(currentNode->next);

            free(currentNode);
 return;
 }



            prevNode = currentNode;
 currentNode = currentNode->next;

            }

I have two questions
regarding this function:

3) Am I "deleting" the
nodes properly? By using free(). Is this the way to do
it?

4) Is this how you link up nodes after
deletion? By setting the next pointer to another
node.

Please assume that malloc will
not return NULL for simplicity. Also note that I have simplified my actual code, else
there is way too much to post, so there might be slight errors. You may also assum that
the while loops will always work (i.e. there will not be a case where
(currentNode->next==NULL). The main point of this post are my questions regarding
whether the method of doing something is
correct.

An example of the program would
be:

-set ex1 2 3 4
5

-get
ex1

2 3 4
5

-set ab 32
112

-get ab

32
112

Thanks in advance.

Answer

strcpy(temp->key, key);
            

For the
the purpose of your program, this is probably ok, but you should use
strncpy(temp->key,key,5) to be safe. Or at least check the length of key to make sure
it fits.

*(temp->data) =
            *(val);

This only sets
the first index in the array. You should use memcpy here.

memcpy (temp->data,val, sizeof
            (int) *
            numOfVal);

Your
print function prints the first element that doesn't match. Did you mean to do the
opposite?

Your delete function does the thing.
It finds the first node that doesn't match.

You
also don't want to free currentNode->next;