C

malloc vs calloc

Both allocates a block of memory, where the primary difference is if block needs to be initialized and if multiple blocks need to be allocated. If initialization isn’t important, use malloc

typedef struct node {
    int val;
    struct node * next;
} node_t;

//create a char pointer ptr 
//using malloc for the allocation of memory
node_t *ptr = (node_t*) malloc(sizeof (node_t)); 

//create a pointer to allocate the memory block using calloc
//assign 10 elements that can hold 10 byte size each
node_t *ptr = (node_t*) calloc(10 ,sizeof (node_t));

If memset is needed after a malloc, use calloc.

memset(ptr, 0, count * sizeof (node_t));

Resource :

• Why does calloc exist

Link list

Link list is a dynamically allocated nodes (a dynamic array).

Advantages over array :

• Items can be added or removed from the middle of the list.
• No need to define an initial size.

Disadvantages :

• No random access. With an array, you can store the index to be able to access the information where as with a linked list it needs to be iterated.
• Dynamic memory and pointers adds a level of complexity.
• Adds a layer of complexity of arrays due to dynamic allocation and pointer storage.

node_t * head = NULL;
head = (node_t *) malloc(sizeof(node_t));
if (head == NULL) {
    return 1;
}

head->val = 1;
head->next = NULL;

void print_list(node_t * head) {
    node_t * current = head;

    while (current != NULL) {
        printf("%d\n", current->val);
        current = current->next;
    }
}

Resources :

• Linked lists