That OTHER time I had to write a linked list in C.

ll.c

#include <stdio.h>
#include <stdlib.h>

//very simple linked list struct
struct ll {
    int x;
    //Add pointer info
	struct ll *next;
	struct ll *prev;
};

//add a node to the list
void add_node(struct ll **list, int y){
    
    //pointers
    struct ll *nn_ptr;
    struct ll *prevn_ptr;
    struct ll *curn_ptr;
    
    //creat space for the new node using malloc
    
    struct ll *newNode = (struct ll*) malloc(sizeof(struct ll));
    
    //if malloc worked, add data
    
	if (newNode != NULL) {
		newNode->x = y;
	}
    
    
    //find the correct location
    curn_ptr = *list;
    prevn_ptr = NULL;
	if (curn_ptr == NULL){
		*list = newNode;
		newNode->next = NULL;
		newNode->prev = NULL;
	}
	else{
    while(curn_ptr->next != NULL){
        curn_ptr = curn_ptr->next;
    }
    
    //insrt the new node
	newNode->next = NULL;
    //firt if at start of the list
        //using our curn_ptr
	newNode->prev = curn_ptr;
	curn_ptr->next = newNode;
    }


}

//remove a node containing y
void remove_node(struct ll **list, int y){
    //pointers
    struct ll *prev_n;
    struct ll *cur_n;
    struct ll *temp;
    
    //check if its the first node
    if((*list)->x == y) {
      //remove the first node

	cur_n = *list;
	cur_n->next = NULL;
	cur_n->prev = NULL;
	temp = cur_n;
	*list = NULL;
	cur_n = NULL;
        //make sure to free the old node
        free(temp);
    }
    else{
        //find the correct node
        prev_n = (*list);
        cur_n = (*list)->next;
        
        while(cur_n->x != y){
		prev_n = cur_n;
		cur_n = cur_n->next;
        }
	if (cur_n->next != NULL) { 
		cur_n->next->prev = prev_n;
	}      
	prev_n->next = cur_n->next;
	temp = cur_n;
	cur_n = *list; //reset cur back to the start of the list for neatness

        }
        free(temp);
        
        
       

}


//print the list
void print_list(struct ll* list){
	struct ll *current;
	
	current = list;
	while (current != NULL){
		printf("%d\n",current->x);
		current = current->next;
	}
}



int main(int argc, const char * argv[]) {
    
    struct ll* test=0;
    add_node(&test, 10);
    add_node(&test, 8);
    add_node(&test, 8);
    add_node(&test, 11);
    add_node(&test, 9);
    print_list(test);
    remove_node(&test, 11);
    print_list(test);
    remove_node(&test, 9);
    print_list(test);
    return 0;
}