Where do I place the NULL character in my function?

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C

I am transferring a linked list of chars into an array of chars, and when I print out the array of chars, i get, along with the string, a garbage int value as such:

2
this0
is1
the6
userfile1
and1
all0
of1
the3
words1
are7
seperated0
by-1
a8
whitespace

I am unsure as to where I must place the null character line in my code.

What I have tried:

fgets(str2, user_file_length, user_file);/*need to assign str2[user_file_length]*/
	token = strtok(str2, " ");
	
	while(token != NULL)
	{
		/*printf( " %s\n", token );*/
		user_list->head = insert_word(user_list, token);
    	token = strtok(NULL, " ");
	}
	printf("\nThe userfile linked list is:\n ");
	display(user_list);
	printf("\n\n");
	
	num_user_words = count(user_list);
	/*code to put userfile linked list into dynamically allocated array*/
	user_array = (char**)malloc(num_user_words*sizeof(char*));
	for(i=0;i<num_user_words;i++)
	{
		put_in_array(user_list, i, user_array);
		printf("\n %s", user_array[i]);
	}

Node* insert_word(Linked_List* list, void* word)
{
	Node* new_node;
	Node* temp;
	char* ptr = malloc(sizeof(word));/*need to free*/
	strcpy(ptr, word);
	new_node = (Node*)malloc(sizeof(Node));/*need to free*/
	new_node->data = ptr;
	new_node->next = NULL;
	if(list->head == NULL)
	{
		list->head = new_node;
	}
	else
	{
		temp = list->head;
		while(temp->next != NULL)
		{
			temp = temp->next;
		}
		temp->next = new_node;
	}
	return(list->head);
}

void put_in_array(Linked_List* list, int element, char** array)
{
	int length;
	int count = 0;
	Node* temp;
	temp = list->head;
	
	while(temp != NULL)
	{
		if(count == element)
		{
			length = strlen((char*)(temp->data))-2;
			printf("%d", length);
			array[count] = (char*)malloc(length*sizeof(char*));
			array[count] = (char*)(temp->data);
			
		}
		count++;
		temp = temp->next;
	}
	
}