list_questions.md

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

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

node* create_node ( int x ) {

    node* n =  malloc (sizeof(node) );
    if (n==NULL) return NULL;

    n->val = x;   
    n->next = NULL;
    return n;   
}

void print_list ( node * h) ;
void add_node ( node** h, int v) ;
int remove_front (node ** h);

int main () {
    node * head = NULL;

    int v = 10;

    for (int i = 0; i < 5; i++) {
        add_node( &head , i * v);
    }

    print_list(head);
    
    while (head)
        printf("removed: %d\n", remove_front(&head));
}

void print_list( node * h) {
    if (h == NULL) return;

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

void add_node( node** h, int v ) {
    if (h==NULL) return;    //invalid list
    
    node * n = create_node(v); 
    
    if (*h == NULL ) {      //empty list 
        *h = n;
        return;
    }
    
    //find the end of the list 
    node * cur = *h;
    while (cur->next != NULL) {
        cur = cur->next;
    }
    cur->next = n; 
}   


int remove_front ( node ** h){
    
    if (h==NULL) return -1;    //invalid list
    
    
    if (*h == NULL ) {      //empty list 
        return -1;
    }
    
    //get the value from the first node and delete that node 
    node * n = *h;
    int val = n->val; 
    *h = (*h)->next; 
    free(n);
    return val; 
}